Methods of Forming Three-Dimensional Structures Having Reduced Stress and/or Curvature

ABSTRACT

Electrochemical fabrication processes and apparatus for producing single layer or multi-layer structures where each layer includes the deposition of at least two materials and wherein the formation of at least some layers includes operations for reducing stress and/or curvature distortion when the structure is released from a sacrificial material which surrounded it during formation and possibly when released from a substrate on which it was formed. Six primary groups of embodiments are presented which are divide into eleven primary embodiments. Some embodiments attempt to remove stress to minimize distortion while others attempt to balance stress to minimize distortion.

RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.11/733,195, filed Apr. 9, 2007. The '195 application claims benefit toU.S. Provisional Patent Application No. 60/790,327, filed Apr. 7, 2006and the '195 application is a continuation-in-part of U.S. patentapplication Ser. No. 10/434,519, filed May 7, 2003; and Ser. No.11/029,220, filed Jan. 3, 2005. The '519 application claims benefit ofU.S. Provisional Patent Application No. 60/379,130, filed May 7, 2002.The '220 application claims benefit of U.S. Provisional PatentApplication Nos. 60/534,159 and 60/534,183, both filed Dec. 31, 2003.These referenced applications are incorporated herein by reference as ifset forth in full herein

FIELD OF THE INVENTION

Embodiments of this invention relate to the field of electrochemicalfabrication and the associated formation of micro-scale or meso-scalesingle layer or multi-layer three-dimensional structures and morespecifically to the use of electrochemical fabrication processes thatproduce three-dimensional single layer or multi-layer structures havingreduced stress, curvature, and/or other stress induced distortions.

BACKGROUND OF THE INVENTION

An electrochemical fabrication technique for forming three-dimensionalstructures from a plurality of adhered layers is being commerciallypursued by Microfabrica Inc. (formerly MEMGen® Corporation) of Van Nuys,Calif. under the name EFAB™.

Various electrochemical fabrication techniques were described in U.S.Pat. No. 6,027,630, issued on Feb. 22, 2000 to Adam Cohen. Someembodiments of this electrochemical fabrication technique allows theselective deposition of a material using a mask that includes apatterned conformable material on a support structure that isindependent of the substrate onto which plating will occur. Whendesiring to perform an electrodeposition using the mask, the conformableportion of the mask is brought into contact with a substrate, but notadhered or bonded to the substrate, while in the presence of a platingsolution such that the contact of the conformable portion of the mask tothe substrate inhibits deposition at selected locations. Forconvenience, these masks might be generically called conformable contactmasks; the masking technique may be generically called a conformablecontact mask plating process. More specifically, in the terminology ofMicrofabrica Inc. such masks have come to be known as INSTANT MASKS™ andthe process known as INSTANT MASKING™ or INSTANT MASK™ plating.Selective depositions using conformable contact mask plating may be usedto form single selective deposits of material or may be used in aprocess to form multi-layer structures. The teachings of the '630 patentare hereby incorporated herein by reference as if set forth in fullherein. Since the filing of the patent application that led to the abovenoted patent, various papers about conformable contact mask plating(i.e. INSTANT MASKING) and electrochemical fabrication have beenpublished:

-   -   (1) A. Cohen, G. Zhang, F. Tseng, F. Mansfeld, U. Frodis and P.        Will, “EFAB: Batch production of functional, fully-dense metal        parts with micro-scale features”, Proc. 9th Solid Freeform        Fabrication, The University of Texas at Austin, p 161, August        1998.    -   (2) A. Cohen, G. Zhang, F. Tseng, F. Mansfeld, U. Frodis and P.        Will, “EFAB: Rapid, Low-Cost Desktop Micromachining of High        Aspect Ratio True 3-D MEMS”, Proc. 12th IEEE Micro Electro        Mechanical Systems Workshop, IEEE, p 244, January 1999.    -   (3) A. Cohen, “3-D Micromachining by Electrochemical        Fabrication”, Micromachine Devices, March 1999.    -   (4) G. Zhang, A. Cohen, U. Frodis, F. Tseng, F. Mansfeld, and P.        Will, “EFAB: Rapid Desktop Manufacturing of True 3-D        Microstructures”, Proc. 2nd International Conference on        Integrated MicroNanotechnology for Space Applications, The        Aerospace Co., April 1999.    -   (5) F. Tseng, U. Frodis, G. Zhang, A. Cohen, F. Mansfeld, and P.        Will, “EFAB: High Aspect Ratio, Arbitrary 3-D Metal        Microstructures using a Low-Cost Automated Batch Process”, 3rd        International Workshop on High Aspect Ratio MicroStructure        Technology (HARMST'99), June 1999.    -   (6) A. Cohen, U. Frodis, F. Tseng, G. Zhang, F. Mansfeld, and P.        Will, “EFAB: Low-Cost, Automated Electrochemical Batch        Fabrication of Arbitrary 3-D Microstructures”, Micromachining        and Microfabrication Process Technology, SPIE 1999 Symposium on        Micromachining and Microfabrication, September 1999.    -   (7) F. Tseng, G. Zhang, U. Frodis, A. Cohen, F. Mansfeld, and P.        Will, “EFAB: High Aspect Ratio, Arbitrary 3-D Metal        Microstructures using a Low-Cost Automated Batch Process”, MEMS        Symposium, ASME 1999 International Mechanical Engineering        Congress and Exposition, November, 1999.    -   (8) A. Cohen, “Electrochemical Fabrication (EFAB™)”, Chapter 19        of The MEMS Handbook, edited by Mohamed Gad-El-Hak, CRC Press,        2002.    -   (9) Microfabrication—Rapid Prototyping's Killer Application”,        pages 1-5 of the Rapid Prototyping Report, CAD/CAM Publishing,        Inc., June 1999.

The disclosures of these nine publications are hereby incorporatedherein by reference as if set forth in full herein.

An electrochemical deposition for forming multilayer structures may becarried out in a number of different ways as set forth in the abovepatent and publications. In one form, this process involves theexecution of three separate operations during the formation of eachlayer of the structure that is to be formed:

-   -   1. Selectively depositing at least one material by        electrodeposition upon one or more desired regions of a        substrate. Typically this material is either a structural        material or a sacrificial material.    -   2. Then, blanket depositing at least one additional material by        electrodeposition so that the additional deposit covers both the        regions that were previously selectively deposited onto, and the        regions of the substrate that did not receive any previously        applied selective depositions. Typically this material is the        other of a structural material or a sacrificial material.    -   3. Finally, planarizing the materials deposited during the first        and second operations to produce a smoothed surface of a first        layer of desired thickness having at least one region containing        the at least one material and at least one region containing at        least the one additional material.

After formation of the first layer, one or more additional layers may beformed adjacent to an immediately preceding layer and adhered to thesmoothed surface of that preceding layer. These additional layers areformed by repeating the first through third operations one or more timeswherein the formation of each subsequent layer treats the previouslyformed layers and the initial substrate as a new and thickeningsubstrate.

Once the formation of all layers has been completed, at least a portionof at least one of the materials deposited is generally removed by anetching process to expose or release the three-dimensional structurethat was intended to be formed. The removed material is a sacrificialmaterial while the material that forms part of the desired structure isa structural material.

The preferred method of performing the selective electrodepositioninvolved in the first operation is by conformable contact mask plating.In this type of plating, one or more conformable contact (CC) masks arefirst formed. The CC masks include a support structure onto which apatterned conformable dielectric material is adhered or formed. Theconformable material for each mask is shaped in accordance with aparticular cross-section of material to be plated (the pattern ofconformable material is complementary to the pattern of material to bedeposited). At least one CC mask is used for each unique cross-sectionalpattern that is to be plated.

The support for a CC mask is typically a plate-like structure formed ofa metal that is to be selectively electroplated and from which materialto be plated will be dissolved. In this typical approach, the supportwill act as an anode in an electroplating process. In an alternativeapproach, the support may instead be a porous or otherwise perforatedmaterial through which deposition material will pass during anelectroplating operation on its way from a distal anode to a depositionsurface. In either approach, it is possible for multiple CC masks toshare a common support, i.e. the patterns of conformable dielectricmaterial for plating multiple layers of material may be located indifferent areas of a single support structure. When a single supportstructure contains multiple plating patterns, the entire structure isreferred to as the CC mask while the individual plating masks may bereferred to as “submasks”. In the present application such a distinctionwill be made only when relevant to a specific point being made.

In preparation for performing the selective deposition of the firstoperation, the conformable portion of the CC mask is placed inregistration with and pressed against a selected portion of (1) thesubstrate, (2) a previously formed layer, or (3) a previously depositedportion of a layer on which deposition is to occur. The pressingtogether of the CC mask and relevant substrate occur in such a way thatall openings, in the conformable portions of the CC mask contain platingsolution. The conformable material of the CC mask that contacts thesubstrate acts as a barrier to electrodeposition while the openings inthe CC mask that are filled with electroplating solution act as pathwaysfor transferring material from an anode (e.g. the CC mask support) tothe non-contacted portions of the substrate (which act as a cathodeduring the plating operation) when an appropriate potential and/orcurrent are supplied.

An example of a CC mask and CC mask plating are shown in FIGS. 1A-1C.FIG. 1A shows a side view of a CC mask 8 consisting of a conformable ordeformable (e.g. elastomeric) insulator 10 patterned on an anode 12. Theanode has two functions. One is as a supporting material for thepatterned insulator 10 to maintain its integrity and alignment since thepattern may be topologically complex (e.g., involving isolated “islands”of insulator material). The other function is as an anode for theelectroplating operation. FIG. 1A also depicts a substrate 6, separatedfrom mask 8, onto which material will be deposited during the process offorming a layer. CC mask plating selectively deposits material 22 ontosubstrate 6 by simply pressing the insulator against the substrate thenelectrodepositing material through apertures 26 a and 26 b in theinsulator as shown in FIG. 1B. After deposition, the CC mask isseparated, preferably non-destructively, from the substrate 6 as shownin FIG. 1C.

The CC mask plating process is distinct from a “through-mask” platingprocess in that in a through-mask plating process the separation of themasking material from the substrate would occur destructively.Furthermore in a through mask plating process, opening in the maskingmaterial are typically formed while the masking material is in contactwith and adhered to the substrate. As with through-mask plating, CC maskplating deposits material selectively and simultaneously over the entirelayer. The plated region may consist of one or more isolated platingregions where these isolated plating regions may belong to a singlestructure that is being formed or may belong to multiple structures thatare being formed simultaneously. In CC mask plating as individual masksare not intentionally destroyed in the removal process, they may beusable in multiple plating operations.

Another example of a CC mask and CC mask plating is shown in FIGS.1D-1G. FIG. 1D shows an anode 12′ separated from a mask 8′ that includesa patterned conformable material 10′ and a support structure 20. FIG. 1Dalso depicts substrate 6 separated from the mask 8′. FIG. 1E illustratesthe mask 8′ being brought into contact with the substrate 6. FIG. 1Fillustrates the deposit 22′ that results from conducting a current fromthe anode 12′ to the substrate 6. FIG. 1G illustrates the deposit 22′ onsubstrate 6 after separation from mask 8′. In this example, anappropriate electrolyte is located between the substrate 6 and the anode12′ and a current of ions coming from one or both of the solution andthe anode are conducted through the opening in the mask to the substratewhere material is deposited. This type of mask may be referred to as ananodeless INSTANT MASK™ (AIM) or as an anodeless conformable contact(ACC) mask.

Unlike through-mask plating, CC mask plating allows CC masks to beformed completely separate from the substrate on which plating is tooccur (e.g. separate from a three-dimensional (3D) structure that isbeing formed). CC masks may be formed in a variety of ways, for example,using a photolithographic process. All masks can be generatedsimultaneously, e.g. prior to structure fabrication rather than duringit. This separation makes possible a simple, low-cost, automated,self-contained, and internally-clean “desktop factory” that can beinstalled almost anywhere to fabricate 3D structures, leaving anyrequired clean room processes, such as photolithography to be performedby service bureaus or the like.

An example of the electrochemical fabrication process discussed above isillustrated in FIGS. 2A-2F. These figures show that the process involvesdeposition of a first material 2 which is a sacrificial material and asecond material 4 which is a structural material. The CC mask 8, in thisexample, includes a patterned conformable material (e.g. an elastomericdielectric material) 10 and a support 12 which is made from depositionmaterial 2. The conformal portion of the CC mask is pressed againstsubstrate 6 with a plating solution 14 located within the openings 16 inthe conformable material 10. An electric current, from power supply 18,is then passed through the plating solution 14 via (a) support 12 whichdoubles as an anode and (b) substrate 6 which doubles as a cathode. FIG.2A illustrates that the passing of current causes material 2 within theplating solution and material 2 from the anode 12 to be selectivelytransferred to and plated on the substrate 6. After electroplating thefirst deposition material 2 onto the substrate 6 using CC mask 8, the CCmask 8 is removed as shown in FIG. 2B. FIG. 2C depicts the seconddeposition material 4 as having been blanket-deposited (i.e.non-selectively deposited) over the previously deposited firstdeposition material 2 as well as over the other portions of thesubstrate 6. The blanket deposition occurs by electroplating from ananode (not shown), composed of the second material, through anappropriate plating solution (not shown), and to the cathode/substrate6. The entire two-material layer is then planarized to achieve precisethickness and flatness as shown in FIG. 2D. After repetition of thisprocess for all layers, the multi-layer structure 20 formed of thesecond material 4 (i.e. structural material) is embedded in firstmaterial 2 (i.e. sacrificial material) as shown in FIG. 2E. The embeddedstructure is etched to yield the desired device, i.e. structure 20, asshown in FIG. 2F.

Various components of an exemplary manual electrochemical fabricationsystem 32 are shown in FIGS. 3A-3C. The system 32 consists of severalsubsystems 34, 36, 38, and 40. The substrate holding subsystem 34 isdepicted in the upper portions of each of FIGS. 3A-3C and includesseveral components: (1) a carrier 48, (2) a metal substrate 6 onto whichthe layers are deposited, and (3) a linear slide 42 capable of movingthe substrate 6 up and down relative to the carrier 48 in response todrive force from actuator 44. Subsystem 34 also includes an indicator 46for measuring differences in vertical position of the substrate whichmay be used in setting or determining layer thicknesses and/ordeposition thicknesses. The subsystem 34 further includes feet 68 forcarrier 48 which can be precisely mounted on subsystem 36.

The CC mask subsystem 36 shown in the lower portion of FIG. 3A includesseveral components: (1) a CC mask 8 that is actually made up of a numberof CC masks (i.e. submasks) that share a common support/anode 12, (2)precision X-stage 54, (3) precision Y-stage 56, (4) frame 72 on whichthe feet 68 of subsystem 34 can mount, and (5) a tank 58 for containingthe electrolyte 16. Subsystems 34 and 36 also include appropriateelectrical connections (not shown) for connecting to an appropriatepower source (not shown) for driving the CC masking process.

The blanket deposition subsystem 38 is shown in the lower portion ofFIG. 3B and includes several components: (1) an anode 62, (2) anelectrolyte tank 64 for holding plating solution 66, and (3) frame 74 onwhich feet 68 of subsystem 34 may sit. Subsystem 38 also includesappropriate electrical connections (not shown) for connecting the anodeto an appropriate power supply (not shown) for driving the blanketdeposition process.

The planarization subsystem 40 is shown in the lower portion of FIG. 3Cand includes a lapping plate 52 and associated motion and controlsystems (not shown) for planarizing the depositions.

In addition to teaching the use of CC masks for electrodepositionpurposes, the '630 patent also teaches that the CC masks may be placedagainst a substrate with the polarity of the voltage reversed andmaterial may thereby be selectively removed from the substrate. Itindicates that such removal processes can be used to selectively etch,engrave, and polish a substrate, e.g., a plaque.

The '630 patent further indicates that the electroplating methods andarticles disclosed therein allow fabrication of devices from thin layersof materials such as, e.g., metals, polymers, ceramics, andsemiconductor materials. It further indicates that although theelectroplating embodiments described therein have been described withrespect to the use of two metals, a variety of materials, e.g.,polymers, ceramics and semiconductor materials, and any number of metalscan be deposited either by the electroplating methods therein, or inseparate processes that occur throughout the electroplating method. Itindicates that a thin plating base can be deposited, e.g., bysputtering, over a deposit that is insufficiently conductive (e.g., aninsulating layer) so as to enable subsequent electroplating. It alsoindicates that multiple support materials (i.e. sacrificial materials)can be included in the electroplated element allowing selective removalof the support materials.

The '630 patent additionally teaches that the electroplating methodsdisclosed therein can be used to manufacture elements having complexmicrostructure and close tolerances between parts. An example is givenwith the aid of FIGS. 14A-14E of that patent. In the example, elementshaving parts that fit with close tolerances, e.g., having gaps betweenabout 1-5 um, including electroplating the parts of the device in anunassembled, preferably pre-aligned, state and once fabricated. In suchembodiments, the individual parts can be moved into operational relationwith each other or they can simply fall together. Once together theseparate parts may be retained by clips or the like.

Another method for forming microstructures from electroplated metals(i.e. using electrochemical fabrication techniques) is taught in U.S.Pat. No. 5,190,637 to Henry Guckel, entitled “Formation ofMicrostructures by Multiple Level Deep X-ray Lithography withSacrificial Metal layers”. This patent teaches the formation of metalstructure utilizing through mask exposures. A first layer of a primarymetal is electroplated onto an exposed plating base to fill a void in aphotoresist (the photoresist forming a through mask having a desiredpattern of openings), the photoresist is then removed and a secondarymetal is electroplated over the first layer and over the plating base.The exposed surface of the secondary metal is then machined down to aheight which exposes the first metal to produce a flat uniform surfaceextending across both the primary and secondary metals. Formation of asecond layer may then begin by applying a photoresist over the firstlayer and patterning it (i.e. to form a second through mask) and thenrepeating the process that was used to produce the first layer toproduce a second layer of desired configuration. The process is repeateduntil the entire structure is formed and the secondary metal is removedby etching. The photoresist is formed over the plating base or previouslayer by casting and patterning of the photoresist (i.e. voids formed inthe photoresist) are formed by exposure of the photoresist through apatterned mask via X-rays or UV radiation and development of the exposedor unexposed areas.

The '637 patent teaches the locating of a plating base onto a substratein preparation for electroplating materials onto the substrate. Theplating base is indicated as typically involving the use of a sputteredfilm of an adhesive metal, such as chromium or titanium, and then asputtered film of the metal that is to be plated. It is also taught thatthe plating base may be applied over an initial layer of sacrificialmaterial (i.e. a layer or coating of a single material) on the substrateso that the structure and substrate may be detached if desired. In suchcases after formation of the structure the sacrificial material formingpart of each layer of the structure may be removed along the initialsacrificial layer to free the structure. Substrate materials mentionedin the '637 patent include silicon, glass, metals, and silicon withprotected semiconductor devices. A specific example of a plating baseincludes about 150 angstroms of titanium and about 300 angstroms ofnickel, both of which are sputtered at a temperature of 160° C. Inanother example it is indicated that the plating base may consist of 150angstroms of titanium and 150 angstroms of nickel where both are appliedby sputtering.

Electrochemical Fabrication provides the ability to form prototypes andcommercial quantities of miniature objects, parts, structures, devices,and the like at reasonable costs and in reasonable times. In fact,Electrochemical Fabrication is an enabler for the formation of manystructures that were hitherto impossible to produce. ElectrochemicalFabrication opens the spectrum for new designs and products in manyindustrial fields. Even though Electrochemical Fabrication offers thisnew capability and it is understood that Electrochemical Fabricationtechniques can be combined with designs and structures known withinvarious fields to produce new structures, certain uses forElectrochemical Fabrication provide designs, structures, capabilitiesand/or features not known or obvious in view of the state of the art.

A need exists in various fields for miniature devices having improvedcharacteristics, reduced fabrication times, reduced fabrication costs,simplified fabrication processes, greater versatility in device design,improved selection of materials, improved material properties, more costeffective and less risky production of such devices, and/or moreindependence between geometric configuration and the selectedfabrication process.

SUMMARY OF THE INVENTION

It is an object of some embodiments of the invention to provide anenhanced electrochemical fabrication process capable of formingstructures with reduced internal stress.

It is an object of some embodiments of the invention to provide anenhanced electrochemical fabrication process capable of formingstructures exhibiting reduced curvature distortion.

Other objects and advantages of various embodiments of the inventionwill be apparent to those of skill in the art upon review of theteachings herein. The various embodiments of the invention, set forthexplicitly herein or otherwise ascertained from the teachings herein,may address one or more of the above objects alone or in combination, oralternatively may address some other object of the invention ascertainedfrom the teachings herein. It is not necessarily intended that allobjects be addressed by any single aspect of the invention even thoughthat may be the case with regard to some aspects.

Each of the first through fourteenth aspects of the invention provide amethod of forming a multi-layer three-dimensional structure, including:(A) forming a plurality of successive layers of the structure with eachsuccessive layer, except for a first layer, adhered to a previouslyformed layer and with each successive layer comprising at least twomaterials, one of which is a structural material and the other of whichis a sacrificial material, and wherein each successive layer defines asuccessive cross-section of the three-dimensional structure, and whereinthe forming of each of the plurality of successive layers includes: (i)depositing a first of the at least two materials; (ii) depositing asecond of the at least two materials; and (B) after the forming of theplurality of successive layers, separating at least a portion of thesacrificial material from the structural material to reveal thethree-dimensional structure.

The first aspect of the invention additionally includes, in associationwith the formation of at least one of the successive layers, dividingthe layer into a first thin sublayer and a second thicker sublayer anddepositing a primary structural material in a lateral region of thefirst sublayer to form at least a portion of the sublayer, andthereafter planarizing the primary structural material to a height thatbounds the first sublayer, where the thickness of the first sublayer issimilar to a known or estimated effective work hardened thickness (e.g.preferably having a thickness between 1/3 and 3 times that of theestimated or known effective work hardened thickness, more preferablybetween 1/2 and 2 times that of the estimated or known effective workhardened thickness, even more preferably within 2/3 and 3/2 times thatof the estimated or known effective work hardened thickness, even morepreferably between 4/5 and 5/4 times that of the estimated or knowneffective work hardened thickness, and most preferably between 9/10 and10/9 times that of the estimated or known effective work hardenedthickness) or less than a known or estimated effective work hardenedthickness induced by the planarization operation, and thereafterdepositing the primary structural material in a lateral region of thesecond sublayer, and thereafter planarizing the primary structuralmaterial of the second sublayer.

The second aspect of the invention additionally includes, in associationwith the formation of at least one of the successive layers, dividingthe layer into a first thin sublayer and a second thicker sublayer,where the thickness of the first sublayer is substantially less thanthat of the second sublayer thickness (e.g. it is preferably less than30%, more preferably less than 20%, and most preferably less than 10% ofthe second sublayer thickness) and depositing a primary structuralmaterial in a lateral region of the first sublayer to form at least aportion of the sublayer, and thereafter planarizing the primarystructural material to a height that bounds the first sublayer, andthereafter depositing the primary structural material in a lateralregion of the second sublayer, and thereafter planarizing the primarystructural material of the second sublayer.

The third aspect of the invention additionally includes, in associationwith the formation of a first layer to which each successive layer willbe adhered, depositing a primary structural material in a lateral regionof the first layer to form at least a portion of the first layer,thereafter planarizing the upper surface of the first layer, prior to orafter forming one or more successive layers, planarizing the bottomsurface of the first layer.

The fourth aspect of the invention additionally includes, forming one ormore successive layers on one or more previously formed layers such thatthe one or more layers are formed on the upper surfaces of the one ormore previously formed layers and then reversing a build orientationsuch that one or more additional layers are formed on the bottom surfaceof a first formed layer of the previously formed layer or layers.

The fifth aspect of the invention additionally includes, in associationwith the formation of at least one of the successive layers, depositinga primary structural material in a lateral region of the layer to format least a majority of the one successive layer in the lateral region,and thereafter planarizing the primary structural material to a heightthat bounds or exceeds the desired height of the at least one successivelayer and such that at least a portion of the primary structuralmaterial is work hardened, etching into the primary structural materialto form one or more openings that extend into the one successive layerin a least a portion of the lateral region to remove at least a portionof the work hardened primary structural material.

The sixth aspect of the invention additionally includes, in associationwith the formation of at least one of the successive layers, depositinga primary structural material in a lateral region of the layer to format least a majority of the one successive layer in the lateral region,and thereafter planarizing the primary structural material to form asurface of the one successive layer, and thereafter sequentiallyexposing portions of the surface to selected radiation that provides theexposed portions with an elevated temperature and results in lessdistortion of the lateral region after the separating than would existin absence of the exposing.

The seventh aspect of the invention additionally includes, inassociation with the formation of at least one of the successive layers,depositing a primary structural material in a lateral region of thelayer to form at least a majority of the one successive layer in thelateral region, and thereafter planarizing the primary structuralmaterial to form a surface of the one successive layer, and thereaftersequentially exposing portions of the surface to selected laserradiation which results in less distortion of the lateral region afterthe separating than would exist in absence of the exposing.

The eighth aspect of the invention additionally includes, in associationwith the formation of at least one of the successive layers, depositinga primary structural material in a lateral region of the layer to format least a majority of the one successive layer in the lateral region,and thereafter planarizing the primary structural material to form asurface of the one successive layer, and thereafter exposing at least aportion of the surface to selected radiation which results in lessdistortion of the lateral region after the separating than would existin absence of the exposing.

The ninth aspect of the invention additionally includes, in associationwith the formation of at least one of the successive layers, depositinga primary structural material in a lateral region of the layer to format least a majority of the one successive layer in the lateral region,and thereafter planarizing the primary structural material to form asurface of the one successive layer, and thereafter applying heat toselected portions of the surface or to the surface as a whole whichresults in less distortion of the lateral region after the separatingthan would exist in absence of the heating

The tenth aspect of the invention additionally includes forming at leastone layer such that a primary structural material on the layer isprovided with an upper surface configuration that is not planar butinstead is made to include a plurality of alternating surface recessionsand elevations (e.g. where the recessions are relatively narrow. e.g.preferably narrower than 10 um, more preferably narrower than 5 um, evenmore preferably thinner than 2 um, and most preferably thinner than 1um) and where the height difference between the recessions andelevations is preferably larger than a depth of work hardening that thesurface of the layer may experience during a planarization operations)which provide decoupling of stress found within the elevations

The eleventh aspect of the invention additionally includes, forming atleast one layer such that a primary structural material on the layer isprovided with an upper surface configuration, planarizing the uppersurface, and thereafter forming notches in the planarized surface in adesired pattern where the notches provide decoupling of stress locatedin separated regions of structural material.

The twelfth aspect of the invention additionally includes, inassociation with the formation of at least one of the successive layers,depositing a primary structural material in a lateral region of thelayer to form the majority of the one successive layer in the lateralregion, wherein the primary structural material is a material thatcannot be planarized reasonably and effectively by diamond fly cuttingand thereafter depositing a secondary structural material in the lateralregion of the one successive layer over the primary structural material,wherein the secondary structural material can be planarized reasonablyand effectively by diamond fly cutting, and then planarizing thesecondary structural material using diamond fly cutting.

The thirteenth aspect of the invention additionally includes, inassociation with the formation of at least one of the successive layers,depositing a primary structural material in a lateral region of thelayer to form the majority of the one successive layer in the lateralregion, and thereafter depositing a secondary structural material in thelateral region of the one successive layer over the primary structuralmaterial, wherein the secondary structural material has a higher tensilestress than the primary structural material, and then planarizing thesecondary structural material without planarizing the primary structuralmaterial.

The fourteenth aspect of the invention additionally includes inassociation with the formation of at least one of the successive layers,depositing a primary structural material in a lateral region of thelayer to form at least a majority of the one successive layer in thelateral region, and thereafter planarizing the primary structuralmaterial to a height that is less than a desired height of the layer andthereafter depositing at least one secondary structural material to thelateral region to bring the height of the deposited primary andsecondary structural materials to a height at least as great as thedesired height of the layer, wherein the secondary structural materialhas a tensile stress greater than a tensile stress of the primarystructural material prior to the planarization of the primary structuralmaterial.

Additional aspects of the invention provide the additions of the abovenoted aspects to the formation of the single layers structures asopposed to multiple layer structures.

Additional aspects of the invention provide products produced by theabove noted method aspects of the invention.

Further aspects of the invention will be understood by those of skill inthe art upon reviewing the teachings herein. Other aspects of theinvention may involve apparatus that can be used in implementing one ormore of the above process aspects of the invention or devices formedusing one of the above process aspects of the invention. These otheraspects of the invention may provide various combinations of theaspects, embodiments, and associated alternatives explicitly set forthherein as well as provide other configurations, structures, functionalrelationships, and processes that have not been specifically set forthabove.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A-1C schematically depict side views of various stages of a CCmask plating process, while FIGS. 1D-G schematically depict a side viewsof various stages of a CC mask plating process using a different type ofCC mask.

FIGS. 2A-2F schematically depict side views of various stages of anelectrochemical fabrication process as applied to the formation of aparticular structure where a sacrificial material is selectivelydeposited while a structural material is blanket deposited.

FIGS. 3A-3C schematically depict side views of various examplesubassemblies that may be used in manually implementing theelectrochemical fabrication method depicted in FIGS. 2A-2F.

FIGS. 4A-4F schematically depict the formation of a first layer of astructure using adhered mask plating where the blanket deposition of asecond material overlays both the openings between deposition locationsof a first material and the first material itself

FIG. 4G depicts the completion of formation of the first layer resultingfrom planarizing the deposited materials to a desired level.

FIGS. 4H and 4I respectively depict the state of the process afterformation of the multiple layers of the structure and after release ofthe structure from the sacrificial material.

FIGS. 5A-5D provides a comparison between a structure, formed from onelayer, that is curvature free and one that has unintended curvaturewhich is released from a substrate.

FIGS. 6A-6D provides a comparison between a structure, formed from twolayers, that is curvature free and one that has unintended curvaturewhere the second layer is cantilevered relative to the first layer andwhere the first layer remains adhered to a substrate.

FIGS. 7A-7D provides a comparison between a structure, formed from twolayers, that is curvature free and one that has unintended curvaturewhich is released from a substrate via a sacrificial release layer (i.e.a material layer) located between structure and the substrate.

FIGS. 8A-8D provides a comparison between a structure, formed from threelayers, that is curvature free and one that has unintended curvaturewhere the second layer is cantilevered relative to the first layer andwherein the first layer remains adhered to a substrate.

FIG. 9 depicts a side view of an example structure where differentportions of the layers of the structure are divided into differentcategories (up-facing, down-facing, both up- and down-facing, orcontinuing) based on their geometric relationship to elements of animmediately succeeding layer and to elements of an immediately precedinglayer.

FIGS. 10A and 10B provide side views of two designs of three-dimensionalstructures that may be cross-sectioned into layers (e.g. eight layers)to produce identical cross-sectional representations that may be thebasis for driving the fabrication of identical three-dimensionalmulti-layer structures.

FIGS. 10C-10M provide examples of how different portions of the variouscross-sections may be categorized differently to define distinctstructural regions so that different fabrication techniques (e.g.curvature reduction techniques) may be applied to the formation ofdistinct portions of the structure.

FIGS. 11A-12B provide side views of cantilever structures supported froma single side where length and thickness requirements are specified forspecial identification or where layers of structural material aredistinguished depending on whether or not they meet the identificationrequirements.

FIGS. 13A-14B provide side views of cantilever structures supported fromboth ends where length and thickness requirements are specified forspecial identification or where layers of structural material aredistinguished depending on whether or not they meet the identificationrequirements.

FIGS. 15A and 15B provide a block diagram setting forth a briefdescription of each of the six groups of embodiments and each of theeleven primary embodiments set forth herein.

FIG. 16 provide block diagram setting forth examples of optionsassociated with fourth embodiment of the invention.

FIG. 17A provides a generalized flowchart of a first embodiment ofinvention where the process of forming at least one layer of thestructure is modified to reduced curvature by forming the at least onelayer from a first sublayer having a thickness that is less than orequal to work hardening thickness and a second sublayer that has athickness that is the layer thickness minus the thickness of the firstsublayer.

FIG. 17B provides a more specific set of steps or operations for aspecific implementation of the first embodiment of the invention.

FIG. 17C provides a variation of the first embodiment of the inventionwhere the curvature reduction technique may be applied to only selectedlateral portions of layers as opposed to the entire layers and where twooptional branches of the process are illustrated

FIGS. 18A-18I depict various states of an implementation of the firstembodiment according to the process of FIG. 17B as applied to theformation of the structure of FIG. 6B where CRP is applied to the entiresecond layer of the structure.

FIG. 19A provides a generalized flowchart of the second embodiment ofthe invention where the structure will be formed, transferred to asecond substrate or carrier, the original substrate or carrier removedand the bottom side of the first layer planarized to induce workhardening therein.

FIG. 20A depicts a side view of a three layer structure made from twodifferent structural materials (e.g. a pin probe formed on its sidehaving a nickel body and a rhodium tip).

FIG. 20B depicts a side view of the structure of FIG. 20A while stillsurrounded by sacrificial material.

FIG. 20C depicts a side view of the structure of FIG. 20B where workhardened upper portions of each layer are indicated (these portions mayresult from planarization of each layer, e.g. by lapping, as it isformed).

FIG. 20D depicts a side view of the structure of FIG. 20B where workhardened upper portions of each layer are indicated and where the bottomportion of the first layer is shown as worked hardened according to anembodiment of the second embodiment of the invention so as to helpbalance any stresses (e.g. compressive forces) within the structure thatmay tend to make the structure curve after release from a buildsubstrate and sacrificial material used in forming the structure.

FIGS. 21A-21V provide side views of various states of an example processinvolved in forming the structure of FIG. 3 according to an embodimentof the invention

FIG. 22A-22F depict states of the process that may replace states21S-21V in an alternative embodiment where a release layer and asubstrate or other carrier is added to the top of the 3rd layer so thatcontinued operations (e.g. planarization of the bottom of the 1st layermay occur.

FIG. 23 provides a flowchart of an implementation of the thirdembodiment of the invention.

FIG. 24A-24H depict states of an example process as applied to a onelayer cantilever structure implementing the fourth embodiment of theinvention where the curvature reduction technique etches away the uppersurface of the second layer and where the etching occurs in either aselective manner (FIG. 24F-1) base on the selectivity of an etchant usedand not on masking (as would be the case in some other embodiments) or anon-selective manner FIG. 24F-2 based on the non-selectivity of andetchant used and where the etched structural material is not replacedvia a subsequent deposition process (as would be the case for somealternative embodiments).

FIGS. 25A-25H depict states of an example process as applied to a onelayer structure implementing the fifth embodiment of the invention whereannealing of the upper surface structural material is used to eliminateor reduced stress and/or curvature distortion.

FIGS. 26A-26F depict states of an example process as applied to either aone layer structure that is divided into two layers or a two layerstructure implementing the seventh embodiment of the invention where theupper sublayer or the second layer has its structural configurationmodified to reduce stress and/or curvature distortion by insertingvertical stress relief into it (in alternative embodiments the breaksmay be implemented so that they only extend into the layer to a depthnecessary to extend through or nearly through any work hardened uppersurface portion of the layer).

FIGS. 27A-27H depict states of an example process as applied to a onelayer cantilever structure 700 (the whole structure is formed with twolayers) implementing the eighth embodiment of the invention where stressinduced in worked hardened regions is isolated by the formation ofbreaks in the worked hardened material after it is formed to eliminateor reduced stress and/or curvature distortion.

FIGS. 28A-28H depict state of an example process as applied to a singlelayer cantilever structure which is divided into two sublayersimplementing the an example of the ninth embodiment where the structuralportion of the layers is formed from two vertically stacked materialswhere planarization of the upper structural material occurs and wherethe upper material is planarizable by a non-stress inducing process(e.g. diamond fly cutting).

FIGS. 29A-29H depict state of an example process as applied to a singlelayer cantilever structure which is divided into two sublayersimplementing an example of the tenth primary embodiment of the inventionwhere the structural portion of the layer is formed from two verticallystacked materials where planarization of the upper structural materialoccurs and where the lower material is deposited in a low stress statewhile the upper material is deposited in a higher tensile stress stateand where the upper material is planarized using a process (e.g.lapping) that introduces compression into the material such that thetensile and compressive forces at least partially cancel one another sothat stress and/or distortion is reduced.

FIGS. 30A-30H depict state of an example process as applied to a singlelayer cantilever structure which is divided into two sublayersimplementing an example of the eleventh primary embodiment of theinvention where the structural portion of the layer is formed from twovertically stacked materials where planarization of the lower structuralmaterial occurs and sets the planed height of the deposited material atsome distance below the desired layer thickness and where theplanarization introduces work hardening into the upper surface of thefirst structural material and thereafter a thin coating of secondstructural material is deposited to raise the height of the depositedmaterials to the desired layer level and wherein the second material ischosen or deposited in such a way that it results in a high tensilestress deposit that helps compensate for the compress stress in the workhardened region of the first material.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Electrochemical Fabrication in General

FIGS. 1A-1G, 2A-2F, and 3A-3C illustrate various features of one form ofelectrochemical fabrication. Other electrochemical fabricationtechniques are set forth in the '630 patent referenced above, in thevarious previously incorporated publications, in various other patentsand patent applications incorporated herein by reference. Still othersmay be derived from combinations of various approaches described inthese publications, patents, and applications, or are otherwise known orascertainable by those of skill in the art from the teachings set forthherein. All of these techniques may be combined with those of thevarious embodiments of various aspects of the invention to yieldenhanced embodiments. Still other embodiments may be derived fromcombinations of the various embodiments explicitly set forth herein.

FIGS. 4A-4I illustrate various stages in the formation of a single layerof a multi-layer fabrication process where a second metal is depositedon a first metal as well as in openings in the first metal so that thefirst and second metal form part of the layer. In FIG. 4A a side view ofa substrate 82 is shown, onto which patternable photoresist 84 is castas shown in FIG. 4B. In FIG. 4C, a pattern of resist is shown thatresults from the curing, exposing, and developing of the resist. Thepatterning of the photoresist 84 results in openings or apertures92(a)-92(c) extending from a surface 86 of the photoresist through thethickness of the photoresist to surface 88 of the substrate 82. In FIG.4D a metal 94 (e.g. nickel) is shown as having been electroplated intothe openings 92(a)-92(c). In FIG. 4E the photoresist has been removed(i.e. chemically stripped) from the substrate to expose regions of thesubstrate 82 which are not covered with the first metal 94. In FIG. 4F asecond metal 96 (e.g. silver) is shown as having been blanketelectroplated over the entire exposed portions of the substrate 82(which is conductive) and over the first metal 94 (which is alsoconductive). FIG. 4G depicts the completed first layer of the structurewhich has resulted from the planarization of the first and second metalsdown to a height that exposes the first metal and sets a thickness forthe first layer. In FIG. 4H the result of repeating the process stepsshown in FIGS. 4B-4G several times to form a multi-layer structure areshown where each layer consists of two materials. For most applications,one of these materials is removed as shown in FIG. 4I to yield a desired3-D structure 98 (e.g. component or device).

Various embodiments of various aspects of the invention are directed toformation of three-dimensional structures from materials some of whichmay be electrodeposited or electroless deposited. Some of thesestructures may be formed form a single build level formed from one ormore deposited materials while others are formed from a plurality ofbuild layers each including at least two materials (e.g. two or morelayers, more preferably five or more layers, and most preferably ten ormore layers). In some embodiments, layer thicknesses may be as small asone micron or as large as fifty microns. In other embodiments, thinnerlayers may be used while in other embodiments, thicker layers may beused. In some embodiments structures having features positioned withmicron level precision and minimum features size on the order of tens ofmicrons are to be formed. In other embodiments structures with lessprecise feature placement and/or larger minimum features may be formed.In still other embodiments, higher precision and smaller minimum featuresizes may be desirable.

The various embodiments, alternatives, and techniques disclosed hereinmay form multi-layer structures using a single patterning technique onall layers or using different patterning techniques on different layers.For example, Various embodiments of the invention may perform selectivepatterning operations using conformable contact masks and maskingoperations (i.e. operations that use masks which are contacted to butnot adhered to a substrate), proximity masks and masking operations(i.e. operations that use masks that at least partially selectivelyshield a substrate by their proximity to the substrate even if contactis not made), non-conformable masks and masking operations (i.e. masksand operations based on masks whose contact surfaces are notsignificantly conformable), and/or adhered masks and masking operations(masks and operations that use masks that are adhered to a substrateonto which selective deposition or etching is to occur as opposed toonly being contacted to it). Conformable contact masks, proximity masks,and non-conformable contact masks share the property that they arepreformed and brought to, or in proximity to, a surface which is to betreated (i.e. the exposed portions of the surface are to be treated).These masks can generally be removed without damaging the mask or thesurface that received treatment to which they were contacted, or locatedin proximity to. Adhered masks are generally formed on the surface to betreated (i.e. the portion of that surface that is to be masked) andbonded to that surface such that they cannot be separated from thatsurface without being completely destroyed damaged beyond any point ofreuse. Adhered masks may be formed in a number of ways including (1) byapplication of a photoresist, selective exposure of the photoresist, andthen development of the photoresist, (2) selective transfer ofpre-patterned masking material, and/or (3) direct formation of masksfrom computer controlled depositions of material.

Patterning operations may be used in selectively depositing materialand/or may be used in the selective etching of material. Selectivelyetched regions may be selectively filled in or filled in via blanketdeposition, or the like, with a different desired material. In someembodiments, the layer-by-layer build up may involve the simultaneousformation of portions of multiple layers. In some embodiments,depositions made in association with some layer levels may result indepositions to regions associated with other layer levels (i.e. regionsthat lie within the top and bottom boundary levels that define adifferent layer's geometric configuration). Such use of selectiveetching and interlaced material deposition in association with multiplelayers is described in U.S. patent application Ser. No. 10/434,519, bySmalley, and entitled “Methods of and Apparatus for ElectrochemicallyFabricating Structures Via Interlaced Layers or Via Selective Etchingand Filling of Voids layer elements” which is hereby incorporated hereinby reference as if set forth in full.

Temporary substrates on which structures may be formed may be of thesacrificial-type (i.e. destroyed or damaged during separation ofdeposited materials to the extent they can not be reused),non-sacrificial-type (i.e. not destroyed or excessively damaged, i.e.not damaged to the extent they may not be reused, e.g. with asacrificial or release layer located between the substrate and theinitial layers of a structure that is formed). Non-sacrificialsubstrates may be considered reusable, with little or no rework (e.g.replanarizing one or more selected surfaces or applying a release layer,and the like) though they may or may not be reused for a variety ofreasons.

Definitions

This section of the specification is intended to set forth definitionsfor a number of specific terms that may be useful in describing thesubject matter of the various embodiments of the invention. It isbelieved that the meanings of most if not all of these terms is clearfrom their general use in the specification but they are set forthhereinafter to remove any ambiguity that may exist. It is intended thatthese definitions be used in understanding the scope and limits of anyclaims that use these specific terms. As far as interpretation of theclaims of this patent disclosure are concerned, it is intended thatthese definitions take presence over any contradictory definitions orallusions found in any materials which are incorporated herein byreference.

“Build” as used herein refers, as a verb, to the process of building adesired structure or plurality of structures from a plurality of appliedor deposited materials which are stacked and adhered upon application ordeposition or, as a noun, to the physical structure or structures formedfrom such a process. Depending on the context in which the term is used,such physical structures may include a desired structure embedded withina sacrificial material or may include only desired physical structureswhich may be separated from one another or may require dicing and/orslicing to cause separation.

“Build axis” or “build orientation” is the axis or orientation that issubstantially perpendicular to substantially planar levels of depositedor applied materials that are used in building up a structure. Theplanar levels of deposited or applied materials may be or may not becompletely planar but are substantially so in that the overall extent oftheir cross-sectional dimensions are significantly greater than theheight of any individual deposit or application of material (e.g. 100,500, 1000, 5000, or more times greater). The planar nature of thedeposited or applied materials may come about from use of a process thatleads to planar deposits or it may result from a planarization process(e.g. a process that includes mechanical abrasion, e.g. lapping, flycutting, grinding, or the like) that is used to remove material regionsof excess height. Unless explicitly noted otherwise, “vertical” as usedherein refers to the build axis or nominal build axis (if the layers arenot stacking with perfect registration) while “horizontal” refers to adirection within the plane of the layers (i.e. the plane that issubstantially perpendicular to the build axis).

“Build layer” or “layer of structure” as used herein does not refer to adeposit of a specific material but instead refers to a region of a buildlocated between a lower boundary level and an upper boundary level whichgenerally defines a single cross-section of a structure being formed orstructures which are being formed in parallel. Depending on the detailsof the actual process used to form the structure, build layers aregenerally formed on and adhered to previously formed build layers. Insome processes the boundaries between build layers are defined byplanarization operations which result in successive build layers beingformed on substantially planar upper surfaces of previously formed buildlayers. In some embodiments, the substantially planar upper surface ofthe preceding build layer may be textured to improve adhesion betweenthe layers. In other build processes, openings may exist in or be formedin the upper surface of a previous but only partially formed buildlayers such that the openings in the previous build layers are filledwith materials deposited in association with current build layers whichwill cause interlacing of build layers and material deposits. Suchinterlacing is described in U.S. patent application Ser. No. 10/434,519.This referenced application is incorporated herein by reference as ifset forth in full. In most embodiments, a build layer includes at leastone primary structural material and at least one primary sacrificialmaterial. However, in some embodiments, two or more primary structuralmaterials may used without a primary sacrificial material (e.g. when oneprimary structural material is a dielectric and the other is aconductive material). In some embodiments, build layers aredistinguishable from each other by the source of the data that is usedto yield patterns of the deposits, applications, and/or etchings ofmaterial that form the respective build layers. For example, datadescriptive of a structure to be formed which is derived from dataextracted from different vertical levels of a data representation of thestructure define different build layers of the structure. The verticalseparation of successive pairs of such descriptive data may define thethickness of build layers associated with the data. As used herein, attimes, “build layer” may be loosely referred simply as “layer”. In manyembodiments, deposition thickness of primary structural or sacrificialmaterials (i.e. the thickness of any particular material after it isdeposited) is generally greater than the layer thickness and a netdeposit thickness is set via one or more planarization processes whichmay include, for example, mechanical abrasion (e.g. lapping, flycutting, polishing, and the like) and/or chemical etching (e.g. usingselective or non-selective etchants). The lower boundary and upperboundary for a build layer may be set and defined in different ways.From a design point of view they may be set based on a desired verticalresolution of the structure (which may vary with height). From a datamanipulation point of view, the vertical layer boundaries may be definedas the vertical levels at which data descriptive of the structure isprocessed or the layer thickness may be defined as the height separatingsuccessive levels of cross-sectional data that dictate how the structurewill be formed. From a fabrication point of view, depending on the exactfabrication process used, the upper and lower layer boundaries may bedefined in a variety of different ways. For example by planarizationlevels or effective planarization levels (e.g. lapping levels, flycutting levels, chemical mechanical polishing levels, mechanicalpolishing levels, vertical positions of structural and/or sacrificialmaterials after relatively uniform etch back following a mechanical orchemical mechanical planarization process). For example, by levels atwhich process steps or operations are repeated. At levels at which, atleast theoretically, lateral extends of structural material can bechanged to define new cross-sectional features of a structure.

“Layer thickness” is the height along the build axis between a lowerboundary of a build layer and an upper boundary of that build layer.

“Planarization” is a process that tends to remove materials, above adesired plane, in a substantially non-selective manner such that alldeposited materials are brought to a substantially common height ordesired level (e.g. within 20%, 10%, 5%, or even 1% of a desired layerboundary level). For example, lapping removes material in asubstantially non-selective manner though some amount of recession onematerial or another may occur (e.g. copper may recess relative tonickel). Planarization may occur primarily via mechanical means, e.g.lapping, grinding, fly cutting, milling, sanding, abrasive polishing,frictionally induced melting, other machining operations, or the like(i.e. mechanical planarization). Mechanical planarization maybe followedor proceeded by thermally induced planarization (.e.g. melting) orchemically induced planarization (e.g. etching). Planarization may occurprimarily via a chemical and/or electrical means (e.g. chemical etching,electrochemical etching, or the like). Planarization may occur via asimultaneous combination of mechanical and chemical etching (e.g.chemical mechanical polishing (CMP)).

“Structural material” as used herein refers to a material that remainspart of the structure when put into use.

“Supplemental structural material” as used herein refers to a materialthat forms part of the structure when the structure is put to use but isnot added as part of the build layers but instead is added to aplurality of layers simultaneously (e.g. via one or more coatingoperations that applies the material, selectively or in a blanketfashion, to a one or more surfaces of a desired build structure that hasbeen released from a sacrificial material.

“Primary structural material” as used herein is a structural materialthat forms part of a given build layer and which is typically depositedor applied during the formation of that build layer and which makes upmore than 20% of the structural material volume of the given buildlayer. In some embodiments, the primary structural material may be thesame on each of a plurality of build layers or it may be different ondifferent build layers. In some embodiments, a given primary structuralmaterial may be formed from two or more materials by the alloying ordiffusion of two or more materials to form a single material.

“Secondary structural material” as used herein is a structural materialthat forms part of a given build layer and is typically deposited orapplied during the formation of the given build layer but is not aprimary structural material as it individually accounts for only a smallvolume of the structural material associated with the given layer. Asecondary structural material will account for less than 20% of thevolume of the structural material associated with the given layer. Insome preferred embodiments, each secondary structural material mayaccount for less than 10%, 5%, or even 2% of the volume of thestructural material associated with the given layer. Examples ofsecondary structural materials may include seed layer materials,adhesion layer materials, barrier layer materials (e.g. diffusionbarrier material), and the like. These secondary structural materialsare typically applied to form coatings having thicknesses less than 2microns, 1 micron, 0.5 microns, or even 0.2 microns). The coatings maybe applied in a conformal or directional manner (e.g. via CVD, PVD,electroless deposition, or the like). Such coatings may be applied in ablanket manner or in a selective manner. Such coatings may be applied ina planar manner (e.g. over previously planarized layers of material) astaught in U.S. patent application Ser. No. 10/607,931. In otherembodiments, such coatings may be applied in a non-planar manner, forexample, in openings in and over a patterned masking material that hasbeen applied to previously planarized layers of material as taught inU.S. patent application Ser. No. 10/841,383. These referencedapplications are incorporated herein by reference as if set forth infull herein.

“Functional structural material” as used herein is a structural materialthat would have been removed as a sacrificial material but for itsactual or effective encapsulation by other structural materials.Effective encapsulation refers, for example, to the inability of anetchant to attack the functional structural material due toinaccessibility that results from a very small area of exposure and/ordue to an elongated or tortuous exposure path. For example, large(10,000 μm²) but thin (e.g. less than 0.5 microns) regions ofsacrificial copper sandwiched between deposits of nickel may defineregions of functional structural material depending on ability of arelease etchant to remove the sandwiched copper.

“Sacrificial material” is material that forms part of a build layer butis not a structural material. Sacrificial material on a given buildlayer is separated from structural material on that build layer afterformation of that build layer is completed and more generally is removedfrom a plurality of layers after completion of the formation of theplurality of layers during a “release” process that removes the bulk ofthe sacrificial material or materials. In general sacrificial materialis located on a build layer during the formation of one, two, or moresubsequent build layers and is thereafter removed in a manner that doesnot lead to a planarized surface. Materials that are applied primarilyfor masking purposes, i.e. to allow subsequent selective deposition oretching of a material, e.g. photoresist that is used in forming a buildlayer but does not form part of the build layer) or that exist as partof a build for less than one or two complete build layer formationcycles are not considered sacrificial materials as the term is usedherein but instead shall be referred as masking materials or astemporary materials. These separation processes are sometimes referredto as a release process and may or may not involve the separation ofstructural material from a build substrate. In many embodiments,sacrificial material within a given build layer is not removed until allbuild layers making up the three-dimensional structure have been formed.Of course sacrificial material may be, and typically is, removed fromabove the upper level of a current build layer during planarizationoperations during the formation of the current build layer. Sacrificialmaterial is typically removed via a chemical etching operation but insome embodiments may be removed via a melting operation orelectrochemical etching operation. In typical structures, the removal ofthe sacrificial material (i.e. release of the structural material fromthe sacrificial material) does not result in planarized surfaces butinstead results in surfaces that are dictated by the boundaries ofstructural materials located on each build layer. Sacrificial materialsare typically distinct from structural materials by having differentproperties therefrom (e.g. chemical etchability, hardness, meltingpoint, etc.) but in some cases, as noted previously, what would havebeen a sacrificial material may become a structural material by itsactual or effective encapsulation by other structural materials.Similarly, structural materials may be used to form sacrificialstructures that are separated from a desired structure during a releaseprocess via the sacrificial structures being only attached tosacrificial material or potentially by dissolution of the sacrificialstructures themselves using a process that is insufficient to reachstructural material that is intended to form part of a desiredstructure. It should be understood that in some embodiments, smallamounts of structural material may be removed, after or during releaseof sacrificial material. Such small amounts of structural material mayhave been inadvertently formed due to imperfections in the fabricationprocess or may result from the proper application of the process but mayresult in features that are less than optimal (e.g. layers with stairssteps in regions where smooth sloped surfaces are desired. In such casesthe volume of structural material removed is typically minusculecompared to the amount that is retained and thus such removal is ignoredwhen labeling materials as sacrificial or structural. Sacrificialmaterials are typically removed by a dissolution process, or the like,that destroys the geometric configuration of the sacrificial material asit existed on the build layers. In many embodiments, the sacrificialmaterial is a conductive material such as a metal. As will be discussedhereafter, masking materials though typically sacrificial in nature arenot termed sacrificial materials herein unless they meet the requireddefinition of sacrificial material.

“Supplemental sacrificial material” as used herein refers to a materialthat does not form part of the structure when the structure is put touse and is not added as part of the build layers but instead is added toa plurality of layers simultaneously (e.g. via one or more coatingoperations that applies the material, selectively or in a blanketfashion, to a one or more surfaces of a desired build structure that hasbeen released from an initial sacrificial material. This supplementalsacrificial material will remain in place for a period of time and/orduring the performance of certain post layer formation operations, e.g.to protect the structure that was released from a primary sacrificialmaterial, but will be removed prior to putting the structure to use.

“Primary sacrificial material” as used herein is a sacrificial materialthat is located on a given build layer and which is typically depositedor applied during the formation of that build layer and which makes upmore than 20% of the sacrificial material volume of the given buildlayer. In some embodiments, the primary sacrificial material may be thesame on each of a plurality of build layers or may be different ondifferent build layers. In some embodiments, a given primary sacrificialmaterial may be formed from two or more materials by the alloying ordiffusion of two or more materials to form a single material.

“Secondary sacrificial material” as used herein is a sacrificialmaterial that is located on a given build layer and is typicallydeposited or applied during the formation of the build layer but is nota primary sacrificial materials as it individually accounts for only asmall volume of the sacrificial material associated with the givenlayer. A secondary sacrificial material will account for less than 20%of the volume of the sacrificial material associated with the givenlayer. In some preferred embodiments, each secondary sacrificialmaterial may account for less than 10%, 5%, or even 2% of the volume ofthe sacrificial material associated with the given layer. Examples ofsecondary structural materials may include seed layer materials,adhesion layer materials, barrier layer materials (e.g. diffusionbarrier material), and the like. These secondary sacrificial materialsare typically applied to form coatings having thicknesses less than 2microns, 1 micron, 0.5 microns, or even 0.2 microns). The coatings maybe applied in a conformal or directional manner (e.g. via CVD, PVD,electroless deposition, or the like). Such coatings may be applied in ablanket manner or in a selective manner. Such coatings may be applied ina planar manner (e.g. over previously planarized layers of material) astaught in U.S. patent application Ser. No. 10/607,931. In otherembodiments, such coatings may be applied in a non-planar manner, forexample, in openings in and over a patterned masking material that hasbeen applied to previously planarized layers of material as taught inU.S. patent application Ser. No. 10/841,383. These referencedapplications are incorporated herein by reference as if set forth infull herein.

“Adhesion layer”, “seed layer”, “barrier layer”, and the like refer tocoatings of material that are thin in comparison to the layer thicknessand thus generally form secondary structural material portions orsacrificial material portions of some layers. Such coatings may beapplied uniformly over a previously formed build layer, they may beapplied over a portion of a previously formed build layer and overpatterned structural or sacrificial material existing on a current (i.e.partially formed) build layer so that a non-planar seed layer results,or they may be selectively applied to only certain locations on apreviously formed build layer. In the event such coatings arenon-selectively applied, selected portions may be removed (1) prior todepositing either a sacrificial material or structural material as partof a current layer or (2) prior to beginning formation of the next layeror they may remain in place through the layer build up process and thenetched away after formation of a plurality of build layers.

“Masking material” is a material that may be used as a tool in theprocess of forming a build layer but does not form part of that buildlayer. Masking material is typically a photopolymer or photoresistmaterial or other material that may be readily patterned. Maskingmaterial is typically a dielectric. Masking material, though typicallysacrificial in nature, is not a sacrificial material as the term is usedherein. Masking material is typically applied to a surface during theformation of a build layer for the purpose of allowing selectivedeposition, etching, or other treatment and is removed either during theprocess of forming that build layer or immediately after the formationof that build layer.

“Multilayer structures” are structures formed from multiple build layersof deposited or applied materials.

“Multilayer three-dimensional (or 3D or 3-D) structures” are MultilayerStructures that meet at least one of two criteria: (1) the structuralmaterial portion of at least two layers of which one has structuralmaterial portions that do not overlap structural material portions ofthe other.

“Complex multilayer three-dimensional (or 3D or 3-D) structures” aremultilayer three-dimensional structures formed from at least threelayers where a line may be defined that hypothetically extendsvertically through at least some portion of the build layers of thestructure will extend from structural material through sacrificialmaterial and back through structural material or will extend fromsacrificial material through structural material and back throughsacrificial material (these might be termed vertically complexmultilayer three-dimensional structures). Alternatively, complexmultilayer three-dimensional structures may be defined as multilayerthree-dimensional structures formed from at least two layers where aline may be defined that hypothetically extends horizontally through atleast some portion of a build layer of the structure that will extendfrom structural material through sacrificial material and back throughstructural material or will extend from sacrificial material throughstructural material and back through sacrificial material (these mightbe termed horizontally complex multilayer three-dimensional structures).Worded another way, in complex multilayer three-dimensional structures,a vertically or horizontally extending hypothetical line will extendfrom one or structural material or void (when the sacrificial materialis removed) to the other of void or structural material and then back tostructural material or void as the line is traversed along at least aportion of the line.

“Moderately complex multilayer three-dimensional (or 3D or 3-D)structures are complex multilayer 3D structures for which thealternating of void and structure or structure and void not only existsalong one of a vertically or horizontally extending line but along linesextending both vertically and horizontally.

“Highly complex multilayer (or 3D or 3-D) structures are complexmultilayer 3D structures for which the structure-to-void-to-structure orvoid-to-structure-to-void alternating occurs once along the line butoccurs a plurality of times along a definable horizontally or verticallyextending line.

“Up-facing feature” is an element dictated by the cross-sectional datafor a given build layer “n” and a next build layer “n+1” that is to beformed from a given material that exists on the build layer “n” but doesnot exist on the immediately succeeding build layer “n+1”. Forconvenience the term “up-facing feature” will apply to such featuresregardless of the build orientation.

“Down-facing feature” is an element dictated by the cross-sectional datafor a given build layer “n” and a preceding build layer “n−1” that is tobe formed from a given material that exists on build layer “n” but doesnot exist on the immediately preceding build layer “n−1”. As withup-facing features, the term “down-facing feature” shall apply to suchfeatures regardless of the actual build orientation.

“Continuing region” is the portion of a given build layer “n” that isdictated by the cross-sectional data for the given build layer “n”, anext build layer “n+1” and a preceding build layer “n−1” that is neitherup-facing nor down-facing for the build layer “n”.

“Minimum feature size” refers to a necessary or desirable spacingbetween structural material elements on a given layer that are to remaindistinct in the final device configuration. If the minimum feature sizeis not maintained on a given layer, the fabrication process may resultin structural material inadvertently bridging the two structuralelements due to masking material failure or failure to appropriatelyfill voids with sacrificial material during formation of the given layersuch that during formation of a subsequent layer structural materialinadvertently fills the void. More care during fabrication can lead to areduction in minimum feature size or a willingness to accept greaterlosses in productivity can result in a decrease in the minimum featuresize. However, during fabrication for a given set of process parameters,inspection diligence, and yield (successful level of production) aminimum design feature size is set in one way or another. The abovedescribed minimum feature size may more appropriately be termed minimumfeature size of sacrificial material regions. Conversely a minimumfeature size for structure material regions (minimum width or length ofstructural material elements) may be specified. Depending on thefabrication method and order of deposition of structural material andsacrificial material, the two types of minimum feature sizes may bedifferent. In practice, for example, using electrochemical fabricationmethods and described herein, the minimum features size on a given layermay be roughly set to a value that approximates the layer thickness usedto form the layer and it may be considered the same for both structuraland sacrificial material widths and lengths. In some more rigorouslyimplemented processes, examination regiments, and rework requirements,it may be set to an amount that is 80%, 50%, or even 30% of the layerthickness. Other values or methods of setting minimum feature sizes maybe set.

“Sublayer” as used herein refers to a portion of a build layer thattypically includes the full lateral extents of that build layer but onlya portion of its height. A sublayer is usually a vertical portion ofbuild layer that undergoes independent processing compared to anothersublayer of that build layer.

Stress, Curvature, and Regions of Structures

When forming structures using the electrochemical fabrication methodsdiscussed above, structures or portions of structures may be formed withunintended curvature. This curvature appears to be more prevalence whenthe thickness between down-facing and overlying up-facing regions isrelatively thin (e.g. under 30-60 microns). It appears as the thicknessof the structural elements increase the tendency to curve decreases asthe overall structure becomes more rigid and less capable of distortingunder the load of any unbalanced stresses that were built into thestructure. The unintended curvature in the structures themselves cannotbe seen prior to the release of the structures (i.e. structuralmaterial) from the surrounding sacrificial materials and possibly fromthe substrate itself. However, at times, unintended curvature can beseen in the build layers themselves particularly when the totalthickness of deposited layers becomes relatively thick (e.g. in excessof 700 to 1500 microns) and the lateral (i.e. horizontal extents whenthe build axis is considered to extend vertically) of the build layersincrease (e.g. beyond 100 mm). The build layer curvature may or may nottranslate into curvature of the build structures themselves depending onthe horizontal dimensions of the build structures themselves, thethickness of the structures, whether or not they remained adhered to thesubstrate, their overall configurations, and the like. Though thisapplication is primarily focused on reducing stress and/or unintendedcurvature in structures themselves, curvature of build layers issomething that can lead to formational difficulties and illustrates theinherent stress, or at least unbalanced stress, that can exist in buildlayers.

Various techniques exist for minimizing build layer curvature. One suchtechnique includes the use of a thick and very rigid substrateparticularly when it is intended that a relatively large thickness ofbuild layers be deposited thereon. Another technique involves theattachment of the substrate to a carrier that tends to stiffen it.Another technique involves the deposition and planarization of materialonto the back side of the substrate during the build process to balancethe stresses that are induced by the build up of layers on the frontside of the substrate. The net amount of material deposited on the backside of the substrate need not be identical to that deposited on thefront side and it need not even be the same material. The materialdeposited onto the back side of the substrate is typically a sacrificialmaterial though it can be structural material or even a mixture ofstructural and sacrificial material. In fact, in some cases it may bepossible to build structures on both sides of the substrate whereinafter formation, the structures on both sides of the substrate arereleased from the sacrificial material and even from the substrate. Ifthe structures are to remain on the substrate they can remain joinedwith their counterparts on the opposite side of the substrate or theycan be separated from their counterparts by slicing the substrate inhalf (i.e. along a horizontal plane through the substrate.

FIGS. 5A-5D provides a comparison between a structure, formed from onelayer, that is curvature free and one that has unintended curvaturewhich is released from a substrate. FIG. 5A provides a schematic sideview of a structure 1204 formed as a single build layer L1 on asubstrate 1202 and which is surrounded by sacrificial material 1206.FIG. 5B depicts the structure 1204 of FIG. 5A as it is intended to lookafter it is separated from the substrate 1202 and sacrificial material1206. FIG. 5C depicts the structure 1202 of FIG. 5A as it is intended tolook after it is separated from the substrate 1202 and sacrificialmaterial 1206 and wherein worked hardened regions 1204B on the upperportion of each layer are shown along with the lower portion 1204A ofstructure 1204. Worked hardened regions 1204B may occur viaplanarization operations that were used to set the upper boundaryportion of the build layer L1 from which the structure was formed. Theplanarization operations setting the boundary level may have involvedone or more lapping operations. FIG. 5D depicts the structure of FIG. 5Aas it may exist after being formed by a prior art technique where thestructure is curved due to excessive unbalanced stresses that wereinduced in the structure during its formation. In particular, the workhardened region 1204B, prior to separation of the structure 1204 fromthe substrate 1202, may experience a compressive stress and uponseparation from the substrate, the layer as a whole may beinsufficiently rigid to resist the release of the compressive stress sothat the stress is relieved by the bending of the structure downwardthereby providing a slight expansion of the upper portion of thestructure and a relief of the compressive force. The structure 1204 ofFIG. 5A may be released from the substrate 1202 via destructive removalof a sacrificial substrate (e.g. dissolution by etching) or via arelease material located between the structure and a non-sacrificialsubstrate (not shown).

FIGS. 6A-6D provides a comparison between a structure, formed from twolayers, that is curvature free and one that has unintended curvaturewhere the second layer is cantilevered relative to the first layer andwhere the first layer remains adhered to a substrate. FIG. 6A provides aschematic side view of a two layer structure 1224, formed from a firstlayer L1 and a second layer L2, attached to a substrate 1222 and whichis surrounded by sacrificial material 1226 and where the structuralmaterial 1224-2 of the second layer extends beyond the structuralmaterial 1224-1 of the first layer L1. FIG. 6B depicts the structure1224 of FIG. 6A as it is intended to look after it is separated from thesacrificial material 1226 which results in a portion 1228 of thestructural material 1224-2 of second layer L2 forming an unsupportedcantilever section relative to the structural material 1224-1 of thefirst layer L1. FIG. 6C depicts the structure 1224 of FIG. 6A as it isintended to look after it is separated from the sacrificial material1226 and wherein worked hardened regions 1224-1B and 1224-2B on theupper portions of the structural material of each of layers L1 and L2are shown as well as the non-work hardened regions 1224-1A and 1224-2A.FIG. 6D depicts the structure 1224 of FIG. 6A as it may exist afterbeing formed by a prior art technique where the unsupported portion 1228(i.e. cantilever portion) of second layer 1224-2 is curved downward dueto excessive unbalanced stresses that were induced in the structure 1224during its formation. As shown in this FIG. 6D, the left side of thestructural material on the second layer L2 appears to be un-distorted asit is constrained by its doubled thicknesses (i.e. the thickness oflayers L1 and L2) and by its attachment to the substrate. As with thestructure 1204 of FIG. 5D, the curvature is downward as a result ofcompressive strain induced in the upper most portion of each layerprobably as a result of surface damage introduced in the upper portionof each layer as a result of a stress inducing planarization process(e.g. lapping) that was used to set the boundary level of the layers.

FIGS. 7A-7D provides a comparison between a structure, formed from twolayers, that is curvature free and one that has unintended curvaturewhich is released from a substrate via a sacrificial release layer (i.e.a material layer) located between structure and the substrate. FIG. 7Aprovides a schematic side view of a two layer structure 1244 attached toa substrate 1242, via a sacrificial layer, L0, 1248 (i.e. a singlematerial layer) and which is surrounded by sacrificial material 1246.The structure is formed from structural material 1244-1, on a firstbuild layer L1, and 1244-2, on a second build layer L2. FIG. 7B depictsthe structure 1244 of FIG. 7A as it is intended to look after it isseparated from the substrate 1242 and sacrificial material 1246. FIG. 7Cdepicts the structure of FIG. 7A as it is intended to look after it isseparated from the substrate and sacrificial material and wherein workhardened regions 1244-1B and 1244-2B on the upper portion of each layerL1 and L2 are shown as well as the non-work hardened regions 1224-1A and1224-2A. FIG. 7D depicts the structure 1244 of FIG. 7A as it may existafter being formed by a prior art technique where the structure 1244 iscurved due to excessive unbalanced stresses that were induced in thestructure during its formation.

FIGS. 8A-8D provides a comparison between a structure, formed from threelayers, that is curvature free and one that has unintended curvaturewhere the second layer is cantilevered relative to the first layer andwherein the first layer remains adhered to a substrate. FIG. 8A providesa schematic side view of a three layer structure 1264 attached to asubstrate 1262 and which is surrounded by sacrificial material 1266 andwhere the structural material 1264-2 and 1264-3 of the second and thirdlayers, L2 and L3, respectively extends beyond the structural material1264-1 of the first layer L1. FIG. 8B depicts the structure 1264 of FIG.8A as it is intended to look after it is separated from the sacrificialmaterial 1266 but remains adhered to the substrate 1262 which results ina portion of the structural material on the second and third layers, L2and L3, defining cantilever 1268 (i.e. a horizontally structure that isunsupported by material existing on previously formed layers). FIG. 8Cdepicts the structure 1264 of FIG. 8A as it is intended to look after itis separated from the sacrificial material and wherein work hardenedregions 1264-1B, 1264-2B, and 1264-3B on the upper portion of each layerL1, L2, and L3 are shown along with regions that are non-work hardened1264-1A, 1264-2A, and 1264-3A. FIG. 8D depicts the structure 1244 ofFIG. 8A as it may exist after being formed by a prior art techniquewhere the unsupported portion 1268 of second and third layers are curveddue to excessive unbalanced stresses that were induced in the structure1264 during its formation.

FIG. 9 depicts a side view of an example structure where differentportions of the layers of the structure are divided into differentcategories (up-facing, down-facing, both up-facing and down-facing, orcontinuing) based on their geometric relationship to elements of animmediately succeeding layer and to elements of an immediately precedinglayer. In FIG. 9, a structure 1284 is shown surrounded by sacrificialmaterial 1286 and adhered to a substrate 1282. For illustrative purposesthe structure is considered to be an extrusion along the y-axis withlayers stacked along the z-axis (i.e. the build axis is the x-axis). Thestructural portion of each layer may be considered to consist of one ormore regions depending on the geometric relationship of the structuralmaterial to structural material on previous and succeeding layers. Theregion portions as illustrate here may consist of down-facing regionsDF, continuation regions C, up-facing regions UF, and regions that reboth up-facing and down facing UF & DF. In the present example thematerial of structure 1284 is considered to be of a single type, e.g.nickel, nickel-cobalt, nickel phosphorus, silver, or the like. In otherembodiments, the structural material on each layer may be different ordifferent on different parts of the same layer. In such cases, regionsdesignations may be base on the distinction between structural materialsand sacrificial material, as above, or may be based on distinctionsbetween different structural materials. In still other cases, otherregion designations may be defined and use. Regions, for example, may bedefined (1) as down-facing for one structural material but also as beingbounded from below by different structural material, (2) as being onlyone layer above a down-facing region, (3) as being only two layers belowan up-facing region. Regions may be distinguished based on a requiredhorizontal width or length. Regions may be divided into boundaryportions and deeper interior portions. A scheme for defining regionsshould take into account at least two criteria: (1) the scheme providessufficient information to allow desired formation techniques to be usedon different portions of each layer, and (2) the desired regions can beadequately identified and distinguished.

FIGS. 10A and 10B provide side views of two designs of three-dimensionalstructures that may be cross-sectioned into layers (e.g. eight layers)to produce identical cross-sectional representations that may be thebasis for driving the fabrication of identical three-dimensionalmulti-layer structures. FIG. 10A depicts a structure 1302 that isdesigned with a stair stepped configuration, along the z-axis, whileFIG. 10B depicts a structure 1312 that has smoothly sloping surfaces1314 along the z-axis. These three-dimensional representations may eachbe converted into a plurality of cross-sectional representations whichmay be useful in driving the fabrication of physical multilayerthree-dimensional structures. As these cross-sectional representationsprovide only a quantized approximation of the original three-dimensionaldesigns, it is conceivable that different approximations are possibledepending on the sophistication of the data processing used and thestructural features that are desired to be emphasized. Rather detailedmethods for distinguishing cross-sectional regions and producingcross-sectional representations of three-dimensional structures thatemphasis different geometric attributes of original structures areprovided in the following U.S. patents: (1) U.S. Pat. No. 5,321,622,entitled “Boolean Layer Comparison Slice”, by Snead et al; and U.S. Pat.No. 6,366,825, entitled “Simultaneous Multiple Layer Curing inStereolithography”, Smalley et al. Each of these patents is incorporatedherein by reference as if set forth in full. If it is desired thatphysically reproduced structures define oversized structures (e.g.structures whose layered solid regions cover all portions of the solidregions of the original design), the basic cross-sectional data and thusthe basic configuration of the structural material associated with eachbuild layer, for the designs of FIGS. 10A and 10B, may be identicalparticularly when these designs are divided into eight cross-sections.

FIGS. 10C-10M provide examples of how different portions of the variouscross-sections may be categorized differently to define distinctstructural regions so that different fabrication techniques (e.g.curvature reduction techniques) may be applied to the formation ofdistinct portions of the structure. The cross-sectional data associatedwith each of these figures is, for example, extractable from thethree-dimensional design of either FIG. 10A or 10B.

FIG. 10C depicts a schematic side view of an example structure formedfrom eight layers, L1-L8, where the structural material portions 1320 ofeach layer are shown with identical patterns which are intended toindicate that each structural material portion is defined as having thesame attributes (e.g. the cross-sectional data for each layer does notdistinguish any special regions of the layers, such as up-facing,down-facing, or continuing regions). Representations of eachcross-section have similar attributes and thus be used to drive anelectrochemical fabrication process according to some embodiments of theinvention where similar curvature reduction techniques will be equallyapplied to all portions of all layers of the structure.

FIG. 10D depicts a schematic side view of an example eight layerstructure where up-facing portions 1322 of the structural material foreach layer are identified differently from non-up-facing portions 1320allowing such data to be used to control the formation of the twoidentified regions differently such that one or the other may be formedusing a curvature reduction technique or such that both may be formedusing different curvature reduction techniques.

FIG. 10E depicts a schematic side view of an example eight layerstructure where special portions 1324 of the structural material 1320 ofthe layers are identified differently from other structural materialportions 1320 when those portions are up-facing and overlay a singlelayer of structure (i.e. the up-facing portions cap a thin portion ofthe structure). In other words the special portions are up-facingregions that do not overlie thick regions of structural material (i.e.structural material thicker than one layer). The cut off thicknessdistinguishing special portions from standard portions is labeled withT1. Such data may be used to control the formation of the two identifiedregions differently such that one or the other may be formed using acurvature reduction technique or such that both may be formed usingdifferent curvature reduction techniques. This data may be used insituations where it is believed that only those portions of a structurethinner than two layer thicknesses are subject to appreciable curvatureor where such portions should be subjected to different curvaturereduction techniques.

FIG. 10F depicts a schematic side view of an example eight layerstructure where special portions 1326 of the structural material of thelayers are identified differently from other structural materialportions 1320 when those portions are up-facing and overlay structuralfeatures thinner than three layer thicknesses (i.e. up-facing regionsthat do not include up-facing regions that overly structural thicknessesof at least three layers) allowing such data to be used to control theformation of the two identified regions differently such that one or theother may be formed using a curvature reduction technique or such thatboth may be formed using different curvature reduction techniques. Thecut off thickness distinguishing special portions from standard portionsis labeled with T1&2.

FIG. 10G depicts a schematic side view of an example eight layerstructure where special portions 1332 and 1334 of the structuralmaterial of layers are identified differently from other structuralmaterial portions 1320. Special portions 1332 define up-facing regionsthat overlay structural material thinner than three layer thicknesses.Special portions 1334 are those portions that immediately underlayup-facing portions where net structural thickness remains less thanthree layer thicknesses. Defining distinct data for three such regionsallows the formation of the structure to occur using up to threedifferent building processes that are geometry specific (e.g. up tothree different curvature reduction techniques. The cut off thicknessdistinguishing special portions from standard portions is labeled withT1&2.

FIG. 10H depicts a schematic side view of an example eight layerstructure where structural material portions of layers containing anup-facing features that overlay structural features thinner than threelayer thicknesses or layers containing non-facing regions thinner thantwo layer thickness 1336 are identified differently from layers notcontaining those regions 1320 thereby allowing such data to be used tocontrol the formation of the two identified regions (i.e. types oflayers) differently and such that one or both may be formed usingsimilar or different curvature reduction techniques. This type ofidentification allows the curvature reduction technique to be selectedon a layer by layer basis depending on the geometric configurationswhich are present on the structural material portion of each layer. Thecut off thickness distinguishing special portions from standard portionsis labeled with T1&2.

FIG. 10I depicts a schematic side view of an example eight layerstructure where up-facing portions 1342 of the structural materialportions of layers that overlay structural material features thinnerthan four layer thicknesses are identified differently from otherregions 1320 (i.e. different from non-up-facing regions and up-facingregions that overly structural thicknesses of at least four layers)allowing such data to be used to control the formation of the twoidentified regions differently such that one or the other may be formedusing a curvature reduction technique or such that both may be formedusing different curvature reduction techniques. The cut off thicknessdistinguishing special portions from standard portions is labeled withT1-3.

FIG. 10J depicts a schematic side view of an example eight layerstructure where up-facing portions 1344 of structural material portionslayers that overlay structural features thinner than four layerthicknesses and underlying non-facing regions 1346 are identifieddifferently from other regions 1320 (i.e. different from thicknon-up-facing regions, i.e. non-up-facing regions at least three layersin thickness, and up-facing regions that overly structural thicknessesof at least four layers) thereby allowing such data to be used tocontrol the formation of the three identified regions differently andsuch that one or more may be formed using similar or different curvaturereduction techniques. The cut off thickness distinguishing specialportions from standard portions is labeled with T1-3.

FIG. 10K depicts a schematic side view of an example eight layerstructure where layers 1348 containing an up-facing feature thatoverlays structural features thinner than four layer thicknesses orlayers containing non-facing regions thinner than three layer thicknessare identified differently from layers not containing those regions.Such identification of layers allows such data to be used to control theformation of the two differently identified regions (in this exampleonly one region results from the specified parameters) differently andsuch that one or both may be formed using similar or different curvaturereduction techniques. The cut off thickness distinguishing specialportions from standard portions is labeled with T1-3.

FIG. 10L depicts a schematic side view of an example eight layerstructure where down-facing portions 1352 of the structural material ofthe layers underlay up-facing portions of the structural material on theimmediately succeeding layer are distinguished differently from otherregions 1320 (i.e. the specially identified portions are those that areboth non-up-facing and which are also less than two layers in thickness)thereby allowing such data to be used to control the formation of thetwo identified regions differently and such that one or both may beformed using different curvature reduction techniques.

FIG. 10M depicts a schematic side view of a final eight layer examplewhere special regions 1354 are identified as those that are (1) notup-facing portions of layers, (2) define portions of the structuralmaterial that having a net thickness less than four layer thicknesses.These special regions 1354 are distinguished from other structuralmaterial portions 1320 (i.e. the specially identified portions are thosethat are both non-up-facing and have thickness of structure that isbelow them of less than the thickness of three layers. Such data may beused to control the formation of the two identified regions differentlyand such that one or both may be formed using different curvaturereduction techniques.

The identification schemes of FIGS. 10D-10G, 10H-10J, 10L, and 10M maybe considered to identify layers containing different feature types aswell as defining specific regions within layers, so that distinctcurvature reduction techniques may be implemented on region-by-regionbasis as previously noted or on a layer-by-layer basis depending on thefeature types present on individual layers.

FIGS. 11A-12B provide side views of cantilever structures supported froma single side where length and thickness requirements are specified forspecial identification or where layers of structural material aredistinguished depending on whether or not they meet the identificationrequirements.

FIG. 11A depicts a schematic side view of an example five layerstructure 1402 where the top two layers (L4 and L5) form a relativeshort cantilever structure 1404 where the length of the cantilever LC isless than a target length TL and where the height of the cantilever iswithin a target height (i.e. less than a target height) and where thetarget length sets a minimum cantilever length beyond which thecantilever may particularly benefit from implementation of a curvaturereduction technique and wherein target height sets a level beyond whicha cantilever structure does not require implementation of a curvaturereduction technique.

FIG. 11B depicts a schematic side view of the structure of FIG. 11Awhere no distinction is made between different portions of any of layersL1-L5 because the structure didn't meet both the thinness and lengthrequirements indicated in FIG. 11A. In alternative examples, specialdistinction may have been granted if only one of the criteria were met.

FIG. 12A depicts a schematic side view of an example five layer L1-L5structure 1412 where the top two layers L4 & L5 form a cantileverstructure 1414 whose length exceed a target length and whose thicknessis within a minimum height range such that the cantilever portion may besubject to excessive curvature upon standard formation and thus maybenefit from application of special formation techniques to help reducecurvature.

FIG. 12B depicts a schematic side view of the structure of FIG. 12Awhere the two layers L4 & L5 forming the thin and long cantilever 1414are shown as being defined differently than the first three layers L1-L3such that the difference may be used to drive structure formation,according to one or more embodiments of the invention, to help minimizedistortion.

FIGS. 13A-14B provide side views of cantilever structures supported fromboth ends where length and thickness requirements are specified forspecial identification or where layers of structural material aredistinguished depending on whether or not they meet the identificationrequirements.

FIG. 13A depicts a schematic side view of an example five layer L1-L5structure 1422 where the structural material of top two layers L4 & L5form a relative short unsupported central bridge 1424 that is supportedon each end by structural material of the third layer L3 where thelength of the unsupported region is less than twice cantilever targetlength TL and where the height of the unsupported portion is within atarget height TH and where the target length sets a minimum cantileverlength (length from each side) beyond which the unsupported portion maybenefit from implementation of a curvature reduction technique andwherein target height sets a level beyond which a cantilever structuredoes not require implementation of a curvature reduction technique.

FIG. 13B depicts a schematic side view of the structure 1422 of FIG. 13Awhere no distinction is made between different portions of any layersbecause the structure didn't meet both the thinness and lengthrequirements indicated in FIG. 13A.

FIG. 14A depicts a schematic side view of an example five layer L1-L5structure 1432 where the top two layers L4 & L5 form an unsupportedcentral bridge 1434 portion where length of the bridge portion from eachend exceeds a target cantilever length TL and whose thickness is withina minimum height range TH such that the cantilever portion 1434 may besubject to excessive curvature upon standard formation and thus maybenefit from application of special formation techniques to help reducecurvature.

FIG. 14B depicts a schematic side view of the structure 1432 of FIG. 14Awhere the two layers L4 and L5 forming the thin but long bridge portion1434 are shown as being defined differently than the first three layersL1-L3 such that the difference may be used to drive structure formation,according to one or more embodiments of the invention, to help minimizedistortion.

Groups and Primary Embodiments

The disclosure of the present invention provides six groups ofembodiments which are further broken into a total of eleven primaryembodiments for reducing stress or curvature distortion. Though theembodiments present herein are focused on forming multi-layerthree-dimensional structures, some of them have application to formingsingle layer structures with less stress and/or less curvature.

FIGS. 15A and 15B provide a block diagram setting forth a briefdescription of the eleven primary embodiments set forth herein.

The primary embodiments 99 of the present invention form multi-layerstructures with reduced curvature distortion by modifying a process thatis used to form at least one layer of the structure or by modifying thedesign of the structure or of at least one layer of the structure. Thefirst group of embodiments 100 (i.e. Group 1) involves the balancing ofstress via creative use of planarization. This group of embodimentsincludes: (1) a first embodiment 101 that includes formation of at leastone layer of the structure that includes a very thin, planarizedsub-layer and a thicker planarized sublayer; (2) a second embodiment 102that includes planarization of the bottom surface of the first layer,and (3) a third embodiment 103 that starts formation of the multi-layerstructure by stacking layers using a building axis with a firstorientation and then continuing the formation with the orientation ofthe building axis reversed.

The first embodiment 101 involves the following operations or steps: (1)Determining the critical layers of a structure (e.g. the bottom of thestructure, layers including extended down-facing regions, etc.) and (2)forming each critical layer as two sublayers. The first sublayer foreach layer has a thickness approximating that of the work hardeningdepth of the planarization operation so that it becomes substantiallycompressively stressed. The second sublayer is thicker so that only itsupper portion is compressively stressed via planarization. The use ofthese two sublayers results in a build layer, as a whole, having morebalanced stress and thus preferably having less distortion or curvature.

The second embodiment 102 involves the formation of a structure bystacking layers one above one another and planarizing the top of eachlayer including the potential of inducing stress in each layer. Forexample, some planarization operations may include the lapping of bothsacrificial and structural materials that form the layer. Afterformation of one or more layers, (e.g. via lapping) and after formationof one or more layers, planarizing the bottom of the first layer usingan appropriate technique to induce a balancing stress therein (e.g. vialapping).

The third embodiment 103 involves forming a structure by stackingsuccessive layers one above one another. Starting with the first layer,the top of each of plurality of layers is planarized with stress beinginduced into each. Planarizing, for example, may occur via lapping.After formation of one or more layers, the orientation of the build axisis reversed and the formation of the structure is continued by addingone or more additional layers to the bottom side of the first layer.During the formation of these additional layers, the top side of one ormore of the additional layers is planarized. With respect to theoriginal orientation, the bottom side of the additional layers isplanarized.

The second group of embodiments 200 includes the reduction of stress inone or more layers of a structure by removal of worked hardenedmaterial. This group of embodiments includes a fourth embodiment 201that involves etching away at least a portion of any work hardenedmaterial and possibly depositing additional material to partially orcompletely fill any void crated by the etching.

The fourth embodiment 201 includes forming structures by depositingmaterials, planarizing the materials, and etching back at least one ofthe materials. The etching back may, for example, be performed witheither wet etching or dry etching. Wet etching may be performedchemically or in some circumstances electrochemically. Dry etching maybe isotropic or anisotropic. If anisotropic, dry etching may beperformed without a mask assuming both structural and sacrificialmaterials are etched at a reasonably uniform rate. The etching may beperformed in a variety of alternative manners, for example: (1) masksmay be used if structural material is being etched and if sacrificialmaterial will be damaged by etchant, (2) masks may use “smaller”openings for etching if edge placement is critical and if etchantattacks the sacrificial material, (3) etching may be applied to onlythose portions of structural material that are non-up-facing surfaces ofthe structure, (4) etching may be applied to regions that arenon-up-facing and that are inset from sidewalls and up-facing regions byan “offset” amount, and/or 5) etching may be applied only to regionswhose net thickness (i.e. thickness between up-facing and down-facingregions) is less than a cut off amount which may be a fixed amount or avariable amount based on length of the region, whether the regions issupported from only one side or opposite sides, the thickness of theregion etc. Additional operations or steps may be optionally performed,for example: (1) material may be re-deposited to non-up-facing regionsduring formation of the next layer, (2) material may be re-deposited toup-facing regions if etching was uniform enough and if re-deposition canoccur in a uniform enough manner, (3) it may be possible to use acombination of alternating etching and plating to remove the stressedmaterial and re-deposit a material having less stressed.

The third group of embodiments 300 involves the removal of stresswithout the removal of the work hardened material. This group ofembodiments includes: (1) a fifth embodiment 301 involving the use offocused heating to anneal work hardened material and a (2) sixthembodiment 302 involving the use of blanket or selective heating toanneal work hardened material.

The fifth embodiment 301 includes the use of focused heating (e.g. froma laser beam) to anneal one or more small lateral regions of the surfaceof the layer preferably to a shallow depth (e.g.˜the depth of workhardening) and then scanning or jumping the focused heating in a desiredpattern over the surface to be annealed. In this embodiment theannealing is preferably, though not necessarily performed prior torelease from any sacrificial material. In this embodiment, the annealingmay occur over only a selected portion of the structural material of thelayer (e.g. the portion that is part of a thin, e.g. less than 50-100um, structural thickness), over all of the structural material of thelayer, or even over both structural and sacrificial material regions.The annealing of this embodiment preferably occurs after planarizationof the layer is completed. However, if sufficient heat is appliedannealing of work hardened material on the previously formed layer mayoccur.

The sixth embodiment 302 includes the use of blanket or selectivelyapplied heating to anneal the surface of a layer preferably to a shallowdepth (e.g.˜the depth of work hardening) potentially using one or moreflash exposures of heat energy. In this embodiment annealing ispreferably, though not necessarily, performed prior to release from anysacrificial material. Selective application may include heating ofdesired structural material regions, heating of all structural materialregions, or heating of selected structural and sacrificial materialregions. The annealing of this embodiment preferably occurs afterplanarization of the layer is completed. However, if sufficient heat isapplied annealing of work hardened material on the previously formedlayer may occur.

The fourth group of embodiments 400 involves the reduction of stress viathe isolation of stress. This group of embodiments includes (1) aseventh embodiment 401 involving modifying the structure by insertingbreaks into what would otherwise be contiguous regions of work hardenedstructural material and (2) an eighth embodiment 402 involves modifyingthe structure by removing selected regions of work hardened material.

The seventh embodiment 401 includes forming a desired structure with atleast one surface (which would be preferentially formed of structuralmaterial in the absence of undesired stress and/or curvature distortion)being formed from alternating regions of structural material with eitherno material or with sacrificial material, wherein the regions of nomaterial or sacrificial material are preferably narrower than theregions of structural material and wherein after planarization thesacrificial material, if present, is removed.

The eighth embodiment 402 includes forming a desired structure with atleast one surface (which would be preferentially formed of continuousstructural material in the absence of undesired stress and/or curvaturedistortion) being formed from structural material and afterplanarization etching, dicing, laser ablation, or otherwise formingnotches in the structural material that are preferably though notnecessarily thin relative to the width of the structural materialislands being formed and wherein the depth of notching is preferably,though not necessarily, thin (e.g.˜the depth of work hardening)

The fifth group of embodiments 500 involves reducing the stress byplanarizing using a non-stress inducing technique or a technique. Thisgroup includes a ninth embodiment 501 involving formation of a layerfrom two structural materials one of which is subject to planarizationand may be planarized without inducing work hardening.

The ninth embodiment 501 includes formation of a layer of a structurewhere first structural material deposited is low stress (compressive ortensile) and where second structural material deposited is low stressand is planarizable by a low or non-stress inducing method (e.g. diamondturning or fly cutting) and where low or non-stress inducingplanarization of the second material occurs leaving a layer havingreduced stress.

The sixth group of embodiments 600 involves reducing stress in a buildlayer which is formed using different materials having different stresslevels after deposition and planarizing one of them. This group ofembodiments includes: (1) a tenth embodiment 601 involving forming abuild layer using a low stress material and a tensile stress material(TSM), & planarizing the TSM and (2) an eleventh embodiment 602involving forming a build layer that deposition of a low stressmaterial, planarization of the low stress material followed bydeposition of a relatively thin TSM.

The tenth embodiment 601 includes formation of a build layer of astructure where a first structural material deposited is low stress(compressive or tensile) and where second structural material depositedis higher tensile stress and where the layer is planarized through thehigher tensile stress material such that compressive stresses induced byplanarization are at least partially balanced so that stress and/orcurvature is reduced.

The eleventh embodiment 602 includes formation of a build layer of astructure where a first structural material deposited is low stress(compressive or tensile) and where the planarization sets the height ofthe material at somewhat less than the desired layer thickness or layerlevel and where compressive stress induced by planarization occurs andthereafter a thin high tensile stress material is deposited to at leastpartially balance the compressive stress and bring the thickness to thelayer thickness or the upper surface of the layer to the desired layerlevel.

FIG. 16 provides a block diagram setting forth examples of optionsassociated with the fourth embodiment of the invention. Similar optionsexist for the other embodiments of the invention.

An Implementation of the First Preferred Embodiment and SomeAlternatives

FIG. 17A provides a generalized flowchart of a first embodiment ofinvention where either (1) the process of forming at least one layer ofthe structure is modified to reduced curvature by forming the at leastone layer from a first sublayer having a thickness that is less than orequal to work hardening thickness and a second sublayer that has athickness that is the layer thickness minus the thickness of the firstsublayer, or (2) the data descriptive of the three-dimensional structureor of cross-sections of the three-dimensional structure are analyzed todetermine if certain criteria are met, such as those exemplified inFIGS. 11D-11M to determine if the curvature reduction process techniqueof the current process should be used.

The process start with block 109 and proceeds to block 110 which callsfor defining the layers n=1 to N which are required to fabricate adesired structure or structures and which calls for defining whichlayers of the structure will receive modified processing for curvatureof stress reduction (i.e. which layers will be processed using curvaturereduction processing or CRP). Block 111 set the value of the layernumber variable “n” equal to one. Block 112 enquires as to whether ornot the current layer “n” will be formed using CRP. If response is “no”,the process moves to block 113 which calls for the formation of layer“n” using a desired formation process (i.e. one that may not be tailoredto reduce curvature or stress). After formation of layer “n” the processmoves forward to block 114 which increments the layer number variable“n” by one (i.e. n=n+1). After block 114 the process moves to theenquiry of block 115 which enquires as to whether n>N, where N is thenumber of the final layer to be formed. If the answer is “yes” theprocess moves to block 116 and ends otherwise it loops back to block112.

If the answer to the enquiry of block 112, for the current layer is“yes” the process moves forward to blocks 117, 118, and 119 to implementthe curvature reduction technique of this embodiment. Block 117, callsfor the division of layer “n” into sublayers “n_(a)” and “n_(b)” where“n_(a)” defines the lower portion of layer “n” and represents a thinlayer that can be made to undergo work hardening (e.g. viaplanarization) through the majority, if not all, of its thickness whilesublayer “n_(b)” defines the majority of the thickness of layer “n”. Inalternative embodiments, the data manipulations of block 117 may beperformed prior to the initiation of any physical formation of thestructure. From block 117 the process moves forward to block 118 whichcalls for the formation of sublayer “na” according to its buildinstructions where deposited materials will be planarized to set theheight of sublayer “n_(a)” equal to the desired height and where theplanarization will cause stress and/or work hardening of the sub layer“n_(a)” through most if not all of its thickness.

After completion of sublayer “n_(a)”, the process moves forward to block119 which calls for the formation of sublayer “n_(b)” where theplanarization process used only work hardens a portion of the thicknessof sublayer “n_(b)”. In effect, this process results in the workhardening or stressing of both the bottom and top of layer “n” whichshould help balance the stress induced in the layer and help reduce annet stress that would lead to curvature of the layer. From step 119 theprocess loops back to block 114. The process is then continued until alllayers 1 to N of the structure are formed.

FIG. 17B provides a more specific set of steps or operations for aspecific implementation of the first embodiment of the invention. Inthis more implementation, blocks that are similar to those in FIG. 17Aare similarly labeled. In this more specific embodiments the steps 113,118, and 119 are further defined to include steps of operations 113-A to113-C, 118-A to 118-C, and 119-A to 119-C, respectively.

Step 113-A calls for the selectively depositing a first materialaccording to a desired pattern of layer “n”, step 113-B calls fordepositing a second material to fill voids in the 1st material on layer“n”, while step calls for planarizing the deposited first and secondmaterials. In the present embodiment, these steps complete the formationof layer “n”. Typically one of the first material or the second materialis a sacrificial material while the other is a structural material. Inother embodiments, different operations/steps may be used in forminglayers.

Step 118-A calls for forming selectively depositing a first materialaccording to a desired pattern of layer “n” with a height appropriatefor yielding a desired thickness of sublayer “n_(a)”, step 118-B callsfor depositing a second material to fill voids in the first material onsublayer “n_(a)”, and step 118-C calls for planarizing the depositedfirst and second materials such that stress/work hardening is introducedinto “n_(a)”. In the present embodiment, these steps complete theformation of sublayer “n_(a)”. Typically one of the first material orthe second material is a sacrificial material while the other is astructural material. In other embodiments, different operations/stepsmay be used in forming sublayer “n_(a)”.

Step 119-A calls for selectively depositing a first material accordingto a desired pattern of layer “n” with a height appropriate for yieldinga desired thickness of sublayer “n_(b)”, step 119-B calls for depositinga second material to fill voids in the first material on sublayer“n_(b)”, and Step 119-C calls for planarizing the deposited first andsecond materials with work hardening introduced into only a minority ofthe thickness of “n_(b)”. In the present embodiment, these stepscomplete the formation of sublayer “n_(b)”. Typically one of the firstmaterial or the second material is a sacrificial material while theother is a structural material. In other embodiments, differentoperations/steps may be used in forming sublayer “n_(b)”.

FIG. 17C provides a variation of the first embodiment of the inventionwhere the curvature reduction technique may be applied to only selectedlateral portions of layers as opposed to the entire layers and where twooptional branches of the process are illustrated. In this alternativeimplementation, blocks that are similar to those in FIG. 17A aresimilarly labeled. In alternative embodiment, step 110 is modified tobecome step 110′ as one does not simply define which layers will receiveCRP but instead individual portions of layers are defined to receiveCRP. Step 120 is inserted between 110′ and 111 and calls for thesupplying of a substrate on which to form layers. The enquiry of step112 is modified to become the enquiry of step 112′ as the question isposed as to whether or not layer “n” has portion that is to receive CRP.If the answer to the enquiry of step 112′ is “yes” the process moveforward to block 121 which enquires as to whether CRP will be applied toall of the layer “n”. If the answer is yes the process moves forward toblocks 117-119 and back to 114, as previously discussed with regard toFIG. 17A. If the answer is “no” the process moves forward to the processmoves forward to block 122. Block 122 calls for the dividing of layer“n” into lateral portions that are to receive curvature reductionprocessing (CRP) and lateral portions that are not to receive CRP. Italso calls for dividing the portion that is to receive CRP into verticalsublayer regions “n_(a)” and “n_(b)”, where “n_(a)” is the lower portionof a CRP region of the layer that undergoes stress hardening throughoutthe majority, and preferably throughout, its entire thickness and where“n_(b)” defines a vertical region above “n_(a)” and has thickness equalto LT_(n)−LT_(na). From Block 122 the process moves forward to block123.

Block 123 calls for forming a sublayer region “n_(a)” according to itsbuild instructions while filling non-CRP structural regions usingsacrificial material, e.g. by selectively depositing a first material,blanket depositing a second material, and planarizing the materialswhere the planarization induces work hardening.

From Block 123 the process moves forward to either block 124-1A or124-2A depending on whether a first option is chosen or a second option.Block 124-1A calls for etching away sacrificial material deposited tothe non-CRP structural material region(s). This etching may be formedselective after masking has occurred. After block 124-1A, the processmoves to block 124-B which calls for forming sublayer “n_(b)” accordingto its build instructions while depositing structural material to fillthe non-CRP structural material region(s) that were initially filledwith sacrificial material, e.g. by selectively depositing a firstmaterial, blanket depositing 2^(nd) material, and then planarizing. Asnoted above the second option takes the process to block 124-2A whichcalls for forming sublayer “n_(b)” according to its build instructionswhile depositing sacrificial material to the non-CRP structural materialregion(s) and thereafter moving to block 124-2B which calls for theetching away of sacrificial material deposited to the non-CRP structuralmaterial region(s) from both the “n_(a)” and “n_(b)” portions of layer“n” after which the process moves forward to block 124-2C which callsfor depositing structural material to the etched region(s) and thenplanarizing.

FIGS. 18A-18I depict various states of an implementation of the firstembodiment according to the process of FIG. 17B as applied to theformation of the structure of FIG. 6B where CRP is applied to the entiresecond layer of the structure.

FIG. 18A depicts a side view of the state of the process after a firstlayer L1 is formed using a structural material 131 and a sacrificialmaterial 141 wherein the upper surface portion 131-B of the structuralmaterial is shown as being different from the remainder 131-A of thestructural material as it has undergone work hardening from aplanarization operation that was used to set the level of the firstlayer.

FIGS. 18B-18E depict states of the process involving the formation ofthe first sublayer of the second layer. FIG. 18B depicts a side view ofthe state of the process after a mask 137 is applied and patterned andafter a structural material 132-A has been deposited as part of forminga first sublayer L2-A of the second layer L2. FIG. 18C depicts a sideview of the state of the process after the mask has been removed. FIG.18D depicts a side view of the state of the process after a blanketdeposit of a sacrificial material 142-A has been made as part of theprocess of forming the first sublayer L2-A of the second layer L2. FIG.18E depicts a side view of the state of the process after the materialsforming the first sublayer L2-A of the second layer L2 have beenplanarized where it is shown that substantially all of the structuralmaterial 132-A′ on the first sublayer L2-A of the second layer hasundergone work hardening.

FIGS. 18F-18H depict states of the process involving formation of thesecond sublayer of the second layer. FIG. 18F depicts a side view of thestate of the process after a mask 147 is applied and patterned and aftera structural material 132-B has been deposited as part of forming asecond sublayer L2-B of the second layer L2. FIG. 18G depicts a sideview of the state of the process after the mask 147 has been removed anda blanket deposit of sacrificial material 142-B has been made as part ofthe process of forming the second sublayer L2-B of the second layer L2.FIG. 18H depicts a side view of the state of the process after thematerials 132-B and 142-B forming the second sublayer L2-B of the secondlayer L2 have been planarized where it is shown that only the topportion of the structural material 132-B′ on the second sublayer of thesecond layer has undergone work hardening.

FIG. 18I depicts a side view of the state of the process after thesacrificial material has been removed to release/reveal thestructure/device formed. FIG. 18I can be compared to 6C to see thedifference in work hardening regions that result from the use of CRP ofthe present embodiment and which it is believed will lead to a reductionin curvature of the structural material portion of the second layer L2after it is released from the sacrificial material.

An Implementation of the Second Preferred Embodiment and SomeAlternatives

FIG. 19 provides a generalized flowchart for the second embodiment ofthe invention where the structure will be formed, transferred to asecond substrate or carrier, the original substrate or carrier removedand the bottom side of the first layer planarized to induce workhardening therein.

The process of FIG. 19 start with block 208 and then moves to block 209which calls for supplying a substrate on which layers will be formed.The process then moves to block 210 which calls for the defining of eachlayer from the first to the Nth from which the structure will be formed.After layers are defined, the process moves forward to block 211 whichcalls for setting the layer number variable equal to one. Next, withblock 212, the “nth” layer is formed according to its buildinstructions. Next the layer number variable “n” is incremented by one(i.e. per block 213, n=n+1). Next the block 214 makes the enquiry as towhether the layer number variable has exceed the number of the finallayer (i.e. has the last layer been formed?). If “no” the process loopsback to block 212, if “yes” the process moves forward to block 215.Block 215 calls for the formation of one or more additional layers ifdesired. Such additional layers may include, for example, a releaselayer. From block 215 the process moves forward to block 216 which callsfor attaching the upper surface of the layer stack (i.e. the uppersurface of the last formed layer) to a temporary substrate or carrier).Next, according to block 217, the original substrate is removed. Theoriginally substrate may have been destructively removed or removed viaa release layer or the like. Next, according to block 218, the bottomsurface of the first layer is planarized in a manner to induce workhardening in it. This is done with the hopes of balancing the stressinduced in the upper portion of each layer, by other planarizationoperations, with the downward stress introduced by this operation.Finally, according to block 220, the structure is separated from thesacrificial material and from the second substrate (if desired) or fromthe carrier. The process then moves forward to block 221 and ends. It isbelieved that the structure will have more balanced stress due to thefinal planarization operation and therefore will have less intendedcurvature.

FIG. 20A depicts a side view of a three layer L1-L3 structure 230 madefrom two different structural materials 232 and 234 (e.g. a pin probeformed on its side having a nickel or nickel cobalt body 232 and arhodium tip 234). The structure may be relatively thin 50-60 microns inheight, or less, and may be subject to significant unintended curvaturewhen formed by an electrodeposition process as discussed herein andreleased from sacrificial material and a substrate on which it wasformed. FIG. 20B depicts a side view of the structure of FIG. 20A whileit is still surrounded by sacrificial material 236.

FIG. 20C depicts a side view of the structure of FIG. 20B where workhardened upper portions of each layer L1-B, L2-B, and L3-B are shownalong with regions that did not undergo significant work hardening L1-A,L2-A, L3-A. The work hardened regions may result from planarization ofeach layer, e.g. by lapping, as it is formed. FIG. 20D depicts a sideview of the structure of FIG. 20B where work hardened upper portions ofeach layer are indicated and where the bottom portion L1-C of the firstlayer is shown as work hardened according to an implementation of thesecond embodiment of the invention so as to help balance any stresses(e.g. compressive forces) within the structure that may tend to make thestructure curve after release from a build substrate and sacrificialmaterial used in forming the structure.

FIGS. 21A-21V provide side views of various states of an example processinvolved in forming the structure of FIGS. 20A & 20B in animplementation of the second embodiment of the invention. This processfalls within process description defined by the flowchart of FIG. 19.

FIGS. 21A-21E depict various states of the process involved in forming afirst layer L1 of the structure where the height of the first layer willnot be completely finalized until after all layers are formed. FIG. 21Adepicts a side view of the state of the process after a photoresist 243has been patterned deposited onto a substrate 242 in preparation forselectively depositing a 1st structural material during formation of a1st layer of the structure. FIG. 21B depicts a side view of the state ofthe process after deposition of the first structural material 244. FIG.21C depicts a side view of the state of the process after removal of thephotoresist 243. FIG. 21D depicts a side view of the state of theprocess after blanket deposition of a sacrificial material 246 that willform a portion of the 1st layer. FIG. 21E depicts a side view of thestate of the process after planarization of the materials deposited onthe first layer L1 but where the resulting height of the first layer isgreater than a desired final height for the first layer. The upperportion 244′ of material 244 is shown differently as it is assumed thatit has been work hardened by the planarization process.

FIGS. 21F-21M depict a side view of various states of the processinvolved informing the second layer L2 of the structure. FIG. 21Fdepicts a side view of the state of the process after application andpatterning of a photoresist 253 in preparation for deposition of a firststructural material 254 for the second layer L2. FIG. 21G depicts a sideview of the state of the process after deposition of the firststructural material 254 associated with the second layer. FIG. 21Hdepicts a side view of the state of the process after removal of thephotoresist 253. FIG. 21I depicts a side view of the state of theprocess after application and patterning of a second photoresist 257 onthe second layer where an opening is created that will allow depositionof a second structural material 255 along side the first structuralmaterial 254 (it may also allow some deposition over the firststructural material if such patterning is necessary to allow appropriateand reliable exposure and development of the photoresist to occur. FIG.21J depicts a side view of the state of the process after deposition ofthe 2nd structural material 255. FIG. 21 k depicts a side view of thestate of the process after removal of the photoresist 257. FIG. 21Ldepicts a side view of the state of the process after deposition ofsacrificial material 256 which will form a part of the second layer.FIG. 21M depicts a side view of the state of the process afterplanarization of the three materials deposited to form the second layerwhere the upper surface 254′ and 255′ of materials 254 and 255 areindicated as being subjected to work hardening and associatedcompressive stress and where the height of the second layer is equal toa desired height of the second layer.

FIGS. 21N-21S depict side view of various states of the processassociated with forming the third layer L3 of the structure. FIG. 21Ndepicts a side view of the state of the process after a photoresist 263is applied and patterned onto the second layer in preparation forselectively depositing a first structural material during formation of athird layer of the structure. FIG. 21O depicts a side view of the stateof the process after deposition of the first structural material 364.FIG. 21P depicts a side view of the state of the process after removalof the photoresist 363. FIG. 21Q depicts a side view of the state of theprocess after blanket deposition of a sacrificial material 366 that willform a portion of the 3rd layer. FIG. 21R depicts a side view of thestate of the process after planarization of the materials deposited onthe third layer where the resulting height of the 3rd layer is equal toa desired height of the third layer and where the upper portion 364′ ofthe structural material 364 is shown as having been work hardened.

FIG. 21S depicts a side view of the state of the process afterattachment of a secondary substrate or carrier 372 (e.g. a vacuumchuck). FIG. 21T depicts a side view of the state of the process afterremoval of the original substrate 242. In some alternative embodimentsthere may have been a release material located between the substrate andthe first layer so that the substrate may be removed in a nondestructivemanner. FIG. 21U depicts a side view of the state of the process afterplanarization of the bottom side of the first layer thereby providingsome balancing compressive work hardening of the structural material244″ on the bottom of the first layer which may tend to reduce theamount of curvature the structure will undergo. FIG. 21V depicts a sideview of the state of the process after the structure is released fromthe sacrificial material and from the secondary substrate or carrier272.

FIG. 22A-22F depict states of the process that may be used to replacestates 21S-21V in an alternative implementation of the second embodimentwhere a release layer and a substrate or other carrier is added to thetop of the 3rd layer so that continued operations (e.g. planarization ofthe bottom of the 1st layer may occur). FIG. 22A depicts the state ofthe process after a release layer 271 of sacrificial material (this is aone material layer) is deposited on top of the third layer. FIG. 22Bdepicts the state of the process after the release layer 271 ofsacrificial material is planarized with the potential work hardenedportion of the release layer is indicated 271′. FIG. 22C depicts thestate of the process after a transfer substrate or carrier 272 is bondedor otherwise attached to the release layer 271. FIG. 22D depicts thestate of the process after the original substrate 242 is removed. FIG.22E depicts a side view of the state of the process after planarizationof the bottom side of the first layer thereby providing some balancingcompressive work hardening 244′ of the bottom of the first layer whichmay tend to reduce the amount of curvature the structure will undergo.FIG. 22F depicts a side view of the state of the process after thestructure is released from the sacrificial material and the releaselayer.

An example of the third embodiment of the invention may be implementedby inserting additional steps into the process of FIG. 19 as shown inblock 219 of FIG. 23.

An Implementation of the Fourth Embodiment of the Invention and SomeAlternatives

FIG. 24A-24H depict states of an example process as applied to a onelayer cantilever structure (the whole structure is formed with twolayers) implementing the fourth embodiment of the invention where thecurvature reduction technique etches away the upper surface of thesecond layer and where the etching occurs in either a selective manner(FIG. 24F1) based on the selectivity of an etchant used and not onmasking (as would be the case in some other embodiments) or anon-selective manner FIG. 24F-2 based on the non-selectivity of andetchant used and where the etched structural material is not replacedvia a subsequent deposition process (as would be the case for somealternative embodiments).

FIG. 24A depicts a side view of the state of the process after formationof a first layer L1, including structural material 404 and sacrificialmaterial 406, on a substrate 402 where it is not indicated whether ornot work hardening of the upper surface of the first layer has occurred.FIG. 24B depicts a side view of the state of the process after a mask417 is formed and a second layer of structural material 412 isdeposited. FIG. 24C depicts a side view of the state of the processafter the mask is removed. FIG. 24D depicts a side view of the state ofthe process after blanket deposition of a sacrificial material 414 isdeposited (in alternative embodiments the order of depositing thestructural and sacrificial material may be reversed). FIG. 24E depicts aside view of the state of the process after the surface of the secondlayer L2 of deposited materials 414 and 416 is planarized at a levelthat is slightly above the desired level for the second layer (assumingthat re-deposition of etched structural material will not occur). Theupper surface 414′ of the structural material 414 is shown as havingbeen work hardened. FIG. 24F-1 depicts a side view of the state of theprocess after a selective etchant primarily attacks and removes theupper surface of the structural material (e.g. the portion of thestructural material that has been work hardened as a result of theplanarization process) to bring the level of the deposit to the boundarylevel of the layer whereas FIG. 24F-2 depicts the state of the processafter a substantially non-selective etchant attacks and removes theupper surface of both the structural and sacrificial materials. FIG. 24Gdepicts the state of the process after the sacrificial material 416 and406 have been removed and where FIG. 24H depicts the state of theprocess after separation of the structure from the substrate 402 (whichmay not occur in some alternative embodiments)

An Implementation of the Fifth Embodiment of the Invention and SomeAlternatives

FIGS. 25A-25H depict states of an example process as applied to a onelayer structure implementing the fifth embodiment of the invention whereannealing of the upper surface of the structural material is used toeliminate or reduced stress and/or curvature distortion. FIG. 25Adepicts a side view of the state of the process after supplying asubstrate 502 on which a layer or layers will be formed. FIG. 25Bdepicts a side view of the state of the process after a release layer503 is formed on the substrate (such a release layer may not benecessary or appropriate in some embodiments). FIG. 25C depicts a sideview of the state of the process after a patterned mask 507 is formedand adhered to the substrate (i.e. to the release layer on thesubstrate). In some alternative embodiments, the mask may be aphotoresist mask which is adhered, exposed, and developed to yielddesired openings. FIG. 25D depicts a side view of the state of theprocess after a structural material 504 is deposited. FIG. 25E depicts aside view of the state of the process after the surface of the maskingmaterial and structural material are planarized (in an alternativeembodiments the masking material may have been removed and a sacrificialmaterial deposited prior to planarization occurring) wherein the uppersurface 504′ of the structural material is shown as having been workhardened. FIG. 25F depicts a side view of the state of the process aftera portion 504″ of the upper surface of the first layer L1 has beenannealed by beam 508 of a laser (not shown). FIG. 25G depicts a sideview of the state of the process after the entire upper surface of thestructural material has annealed to yield 504″. FIG. 25H depicts thestate of the process after the mask and substrate have been separatedfrom the structural material 504/504″ to yield structure 500.

As with the other embodiments, presented herein, the sixth embodimentmay be implemented in a number of different ways. The heating thatinduces annealing may (1) expose the entire upper surface of the layer,(2) a mask may be formed on the upper surface of the layer to shieldportions of the layer, (3) be supplied via an array of sources so withonly selected sources powered. Various other alternatives are alsopossible and will be understood by those of skill in the art.

An Implementation of the Seventh Embodiment of the Invention and SomeAlternatives

FIGS. 26A-26F depict states of an example process as applied to either aone layer structure that is divided into two layers or a two layerstructure implementing an example of the seventh embodiment of theinvention where the upper sublayer or the second layer has itsstructural configuration modified to reduce stress and/or curvaturedistortion by inserting vertical stress reliefs into it (in alternativeembodiments the breaks may be implemented so that they only extend intothe layer to a depth necessary to extend through or nearly through anywork hardened upper surface portion of the layer). FIG. 26A depicts aside view of the state of the process after supplying a substrate 702 onwhich a layer or layers of a structure will be formed, after a releaselayer 703 is formed on the substrate (such a release layer may not benecessary or appropriate in some embodiments), after a patterned mask707 is formed and adhered to the substrate (i.e. to the release layer onthe substrate), and after a structural material 704 is deposited to forma first layer or first sublayer of the first layer. FIG. 26B depicts aside view of the state of the process after a second layer or secondsublayer of masking material 717 is applied to the surface of the firstlayer or first sublayer and patterned to form breaks 715 at periodicintervals along region that would be occupied by structural material ifit were not for the stress and/or curvature that the process isattempting to minimize. FIG. 26C depicts a side view of the state of theprocess after plating of structural material 714 (e.g. nickel or anickel alloy) into the openings in the mask 717. FIG. 26D depicts a sideview of the state of the process after planarization of the uppersurface of the second layer or second sublayer is performed to set theheight of the second layer or second sublayer at the boundary level forthat layer or sublayer. FIG. 26E depicts a side view of the state of theprocess after the mask and substrate have been separated from thestructural material while FIG. 26F depicts a top view of the same stateof the process (in this example it is noted that the notches formed inthe upper surface extend in a single direction perpendicular to thelength of the structure so as to maximize the stress relief that hasoccurred while in other embodiments other patterns of notches may beused and in still other embodiments, the notches may be filled with amaterial, e.g. by spreading, wiping clean, and solidifying.

An Implementation of the Eight Embodiment of the Invention and SomeAlternatives

FIGS. 27A-27H depict states of an example process as applied to a onelayer cantilever structure 700 (the whole structure is formed with twolayers) implementing the eighth embodiment of the invention where stressinduced in worked hardened regions is isolated by the formation ofbreaks in the worked hardened material after it is formed to eliminateor reduced stress and/or curvature distortion. The breaks that areformed in the upper surface of the second layer of this example, may bedesigned into the structure or may be placed in the structure byimplementation of an algorithm that modifies the structure based on apre-designed pattern or based on a pattern that is created in responseto design parameters specified by the builder in order optimize stressand/or curvature reduction.

FIG. 27A depicts a side view of the state of the process after formationof a first layer L1, including structural material 704 and sacrificialmaterial 706, on a substrate 702 where it is not indicated whether ornot work hardening of the upper surface of the first layer has occurred(it is irrelevant to this example as if is intended to only deal withwork hardening that has occurred on the second layer. FIG. 27B depicts aside view of the state of the process after a mask 717 is formed and asecond layer of structural material 714 is deposited. FIG. 27C depicts aside view of the state of the process after the mask is removed. FIG.27D depicts a side view of the state of the process after blanketdeposition of a sacrificial material 716 is deposited (in alternativeembodiments the order of depositing the structural and sacrificialmaterial may be reversed). FIG. 27E depicts a side view of the state ofthe process after the surface of the second layer L2 of depositedmaterials 714 and 716 is planarized at a level that is slightly abovethe desired level for the second layer (assuming that re-deposition ofetched structural material will not occur). The upper surface 714′ ofthe structural material 714 is shown as having been work hardened. FIG.27F depicts a side view of the state of the process after selectivelyremoval of at least a desired depth of work hardened material has beenremoved, for example via patterned etching (dry or wet), partial depthdicing, laser ablation, or the like, FIGS. 27G and 27H depict the stateof the process after removal of the sacrificial material and substraterespectively to yield the structure 700.

As with the other embodiments, presented herein, this embodiment may beimplemented in a number of different ways including use of the CRP on aplurality of layers (instead of just the one illustrate). The stressrelief gaps may filled in with a material that does not reintroducestress, reintroduces less stress or even introduces stress that isopposite to that induced by the work hardening.

An Implementation of the Ninth Embodiment of the Invention and SomeAlternatives

FIGS. 28A-28G-2 depict the state of an example process as applied to asingle layer cantilever structure, which is formed along with a post,where the layer of the cantilever structure is divided into twosublayers implementing the an example of the ninth embodiment where thestructural portion of the layers is formed from two vertically stackedmaterials where planarization of the upper structural material occursand where the upper material is planarizable by a non-stress inducingprocess (e.g. diamond fly cutting).

FIG. 28A depicts a side view of the state of the process after formationof a first layer L1 where it is not indicated whether or not workhardening of the upper surface of the first layer has occurred as it isnot relevant to the present example as the CRP is only to be implementin conjunction with formation of the second layer. FIG. 28B depicts aside view of the state of the process after a mask 917 is formed and afirst portion (e.g. sublayer of the second layer) of a first structuralmaterial 914-A is deposited, where the first structural material 914-Ais a material that cannot be readily planarized (e.g. nickel, or nickelcobalt, rhodium, or the like) without inducing significant stress intoit. FIG. 28C depicts a side view of the state of the process after asecond structural material 914-B is deposited over the first structuralmaterial, wherein the second structural material is a material (e.g.amorphous nickel phosphorus) that can be readily planarized withoutinducing significant stress (e.g. by diamond fly cutting). FIG. 28Ddepicts a side view of the state of the process after the mask isremoved. FIG. 28E depicts a side view of the state of the process afterblanket deposition of a sacrificial material 716 has occurred (inalternative embodiments the order of depositing the structural andsacrificial material may be reversed). FIG. 28F depicts a side view ofthe state of the process after the surface of the second structuralmaterial 914-B is planarized at a level that corresponds to the boundaryof the layer using a non-stress inducing planarization process. FIG. 28Gdepicts the state of the process after the sacrificial material has beenremoved and where FIG. 28H depicts the state of the process afterseparation of the structure 900 from the substrate (which may not occurin some alternative embodiments).

As with the other embodiments, presented herein, this embodiment may beimplemented in a number of different ways including use of the CRP on aplurality of layers (instead of just the one illustrated). In someembodiments it may be acceptable if some portion of the material 914-Areaches the planarization level so long as it doesn't represent a largearea that could negatively impact the effectiveness of the planarizationprocess.

An Implementation of the Tenth Embodiment of the Invention and SomeAlternatives

FIGS. 29A-29H depict the states of an example process as applied to asingle layer cantilever structure which is divided into two sublayersimplementing an example of the tenth primary embodiment of the inventionwhere the structural portion of the layer is formed from two verticallystacked materials where planarization of the upper structural materialoccurs and where the lower material is deposited in a low stress statewhile the upper material is deposited in a higher tensile stress stateand where the upper material is planarized using a process (e.g.lapping) that introduces compression into the material such that thetensile and compressive forces at least partially cancel one another sothat stress and/or distortion is reduced.

FIG. 29A depicts a side view of the state of the process after formationof a first layer that includes structural material 1004 and sacrificialmaterial 1006 which have been deposited on substrate 1002 and thenplanarized. In this figure it is not indicated whether or not workhardening of the upper surface of the first layer has occurred as it isirrelevant to the present example as CRP is only intended to be appliedto the second layer. FIG. 29B depicts a side view of the state of theprocess after a mask is formed and a first structural material 1014-A(e.g. first sublayer of the second layer) is deposited, where the firststructural material 1014-A is a material that is preferably depositedwith minimal tensile or compressive stress. FIG. 29C depicts a side viewof the state of the process after a second structural material 1014-B isdeposited over the first structural material, wherein the secondstructural material is deposited with significant tensile stress. FIG.29D depicts a side view of the state of the process after the mask isremoved. FIG. 29E depicts a side view of the state of the process afterblanket deposition of a sacrificial material 1016 occurs(in alternativeembodiments the order of depositing the structural and sacrificialmaterial may be reversed). FIG. 29F depicts a side view of the state ofthe process after the surface of the second structural material 1014-Bis planarized at a level that corresponds to the boundary of the layer.Planarization includes use of process that induces compressive stressinto the second material, wherein after planarization substantially allof or at least most of the remaining second material undergoes workhardening (which tends to induce compressive stress). FIG. 29G depictsthe state of the process after the sacrificial material has been removedand where FIG. 29H depicts the state of the process after separation ofthe structure 1000 from the substrate (which may not occur in somealternative embodiments).

As with the other embodiments, presented herein, this embodiment may beimplemented in a number of different ways including use of the CRP on aplurality of layers (instead of just the one illustrated).

An Implementation of the Eleventh Embodiment of the Invention and SomeAlternatives

FIGS. 30A-30H depict state of an example process as applied to a singlelayer cantilever structure which is formed on a post and which isdivided into two sublayers implementing an example of the eleventhprimary embodiment of the invention where the structural portion of thelayer is formed from two vertically stacked materials whereplanarization of the lower structural material occurs and sets theplanned height of the deposited material at some distance below thedesired layer thickness and where the planarization introduces workhardening into the upper surface of the first structural material andthereafter a thin coating of second structural material is deposited toraise the height of the deposited materials to the desired layer leveland wherein the second material is chosen or deposited in such a waythat it results in a high tensile stress deposit that helps compensatefor the compressive stress in the work hardened region of the firstmaterial.

FIG. 30A depicts a side view of the state of the process after formationof a first layer that includes structural material 1104 and sacrificialmaterial 1106 which were deposited onto substrate 1102 where it is notindicated whether or not work hardening of the upper surface of thefirst layer has occurred as it is irrelevant to the present example asthe CRP is only to be applied to the second layer. FIG. 30B depicts aside view of the state of the process after a mask 1117-A is formed anda first structural material 1114-A (e.g. first sublayer of the secondlayer) is deposited, where the first structural material is a materialthat is preferably deposited with minimal tensile or compressive stress.FIG. 30C depicts a side view of the state of the process after the maskis removed. FIG. 30D depicts a side view of the state of the processafter blanket deposition of a sacrificial material 1116 occurs (inalternative embodiments the order of depositing the structural andsacrificial material may be reversed). FIG. 30E depicts a side view ofthe state of the process after the surface of the first structuralmaterial 1114-A is planarized at a level that is somewhat below thedesired boundary level of the layer using a planarization process thatinduces compressive stress into the first structural material, whereinplanarization induces work hardening in only a portion 1114-A′ of thethickness of the deposit of the first structural material. FIG. 30Fdepicts a side view of the state of the process after mask 1117-B isapplied and a thin, high tensile stress coating of a second structuralmaterial 1114-B is deposited over work hardened portion 1114-A′ of thefirst structural material. The amount of material 1114-B that isdeposited is thin and it is believed it can be deposited with asufficient uniform texture so as to no require further planarization.The second material 1114-B either inherently has a high tensile stressor is deposited in such away so as to incur a high tensile stress. It isbelieved that such stressing can help to compensate for the compressivestress induced in the upper portion 1114-A′ of the first structuralmaterial such that stress and/or curvature distortion is reduced. FIG.30G depicts the state of the process after the sacrificial material hasbeen removed and FIG. 30H depicts the state of the process afterseparation of the structure 1100 from the substrate (which may not occurin some alternative embodiments).

As with the other embodiments, presented herein, this embodiment may beimplemented in a number of different ways including use of the CRP on aplurality of layers (instead of just the one illustrated).

Further Alternatives and Conclusions:

The various embodiments explicitly set forth in this application maytake on a variety of alternative forms. For example, the orders ofdepositing structural and sacrificial material may be varied, differentnumbers of sacrificial and structural materials may be used, differentmechanical, chemical, and electrochemical etching and planarizationprocesses may be used. Depositions may be made using electrochemicaltechniques, electroless deposition techniques, sputtering, spraying,spreading, as well as via other processes. Electrochemical depositionmay take the form of electroplating of fixed current density, pulsedelectroplating, reverse pulse plating.

Curvature reduction processes may involve or additionally includetechniques to change grain structure within layers, such as for example,reverse pulse plating, formation of grain nucleation sites within alayer. Curvature reduction processes may involve theoretical orempirically determined process parameters that are optimized for a givensituation. Though a portion of this application has been written basedon the assumption that work hardening occurs near the surface of somematerials (e.g. nickel, nickel-cobalt, other nickel alloys, and thelike) when subjected to some planarization processes (e.g. lapping), theeffectiveness of any stress reduction process or curvature reductionprocess should dictate the appropriateness of the process and notwhether the assumed work hardening theory is determined to be accurate,inaccurate, or simply incomplete.

The curvature reduction techniques may be implemented on a critical orselected region basis, critical of selected layer basis, based onlocations or layers containing up-facing regions, locations or layerscontaining non-up-facing regions, regions that are thin relative to apredefined value, regions have length to thickness aspect ratio thatmeet or do not meet certain criteria. Rework of layers that aredetermined to be, or are suspected of being faulty may be performed.

It will be understood by those of skill in the art or will be readilyascertainable by them that various additional operations may be added tothe processes set forth herein. For example, between performances of thevarious deposition operations, the various etching operations, and thevarious planarization operations cleaning operations, activationoperations, and the like may be desirable.

Some embodiments may employ diffusion bonding or the like to enhanceadhesion between successive layers of material. Various teachingsconcerning the use of diffusion bonding in electrochemical fabricationprocesses are set forth in U.S. patent application Ser. No. 10/841,384which was filed May 7, 2004 by Cohen et al. which is entitled “Method ofElectrochemically Fabricating Multilayer Structures Having ImprovedInterlayer Adhesion” and which is hereby incorporated herein byreference as if set forth in full. This application is herebyincorporated herein by reference as if set forth in full.

Further teachings about planarizing layers and setting layersthicknesses and the like are set forth in the following US PatentApplications which were filed Dec. 31, 2003: (1) U.S. Patent ApplicationNo. 60/534,159 by Cohen et al. and which is entitled “ElectrochemicalFabrication Methods for Producing Multilayer Structures Including theuse of Diamond Machining in the Planarization of Deposits of Material”and (2) U.S. Patent Application No. 60/534,183 by Cohen et al. and whichis entitled “Method and Apparatus for Maintaining Parallelism of Layersand/or Achieving Desired Thicknesses of Layers During theElectrochemical Fabrication of Structures”. The techniques disclosedexplicitly herein may benefit by combining them with the techniquesdisclosed in U.S. patent application Ser. No. 11/029,220, filed Jan. 3,2005 by Frodis, et al., and which is entitled “Method and Apparatus forMaintaining Parallelism of Layers and/or Achieving Desired Thicknessesof Layers During the Electrochemical Fabrication of Structures”. Thesepatent filings are each hereby incorporated herein by reference as ifset forth in full herein.

Additional teachings concerning the formation of structures ondielectric substrates and/or the formation of structures thatincorporate dielectric materials into the formation process andpossibility into the final structures as formed are set forth in anumber of patent applications: (1) U.S. Patent Application No.60/534,184, by Cohen, which as filed on Dec. 31, 2003, and which isentitled “Electrochemical Fabrication Methods Incorporating DielectricMaterials and/or Using Dielectric Substrates”; (2) U.S. PatentApplication No. 60/533,932, by Cohen, which was filed on Dec. 31, 2003,and which is entitled “Electrochemical Fabrication Methods UsingDielectric Substrates”; (3) U.S. Patent Application No. 60/534,157, byLockard et al., which was filed on Dec. 31, 2004, and which is entitled“Electrochemical Fabrication Methods Incorporating DielectricMaterials”; (4) U.S. Patent Application No. 60/574,733, by Lockard etal., which was filed on May 26, 2004, and which is entitled “Methods forElectrochemically Fabricating Structures Using Adhered Masks,Incorporating Dielectric Sheets, and/or Seed Layers that are PartiallyRemoved Via Planarization”; and U.S. Patent Application No. 60/533,895,by Lembrikov et al., which was filed on Dec. 31, 2003, and which isentitled “Electrochemical Fabrication Method for Producing Multi-layerThree-Dimensional Structures on a Porous Dielectric”. The techniquesdisclosed explicitly herein may benefit by combining them with thetechniques disclosed in U.S. patent application Ser. No. 11/029,216filed Jan. 3, 2005 by Cohen et al. and entitled “ElectrochemicalFabrication Methods Incorporating Dielectric Materials and/or UsingDielectric Substrates”. These patent filings are each herebyincorporated herein by reference as if set forth in full herein.

Some embodiments may not use any blanket deposition process. Someembodiments may involve the selective deposition of a plurality ofdifferent materials on a single layer or on different layers. Someembodiments may use blanket or selective depositions processes that arenot electrodeposition processes. Some embodiments may form structuresfrom two or more materials where one or more of the materials are coatedwith thin deposits of dielectric material and one or more materials aretreated as a sacrificial material and removed after the formation of aplurality of layers. Some embodiments may use nickel or a nickel alloyas a structural material while other embodiments may use differentmaterials such as gold, silver, or any other electrodepositable orelectroless depositable materials. Some embodiments may use copper asthe structural material with or without a sacrificial material. Someembodiments may remove a sacrificial material while other embodimentsmay not.

Though various portions of this specification have been provided withheaders, it is not intended that the headers be used to limit theapplication of teachings found in one portion of the specification fromapplying to other portions of the specification. For example, it shouldbe understood that alternatives acknowledged in association with oneembodiment, are intended to apply to all embodiments to the extent thatthe features of the different embodiments make such applicationfunctional and do not otherwise contradict or remove all benefits of theadopted embodiment. Various other embodiments of the present inventionexist. Some of these embodiments may be based on a combination of theteachings herein with various teachings incorporated herein byreference.

As noted above, embodiments of the invention may take a variety of formssome of which have been set forth herein in detail while others aredescribed or summarized in a more cursory manner, while still otherswill be apparent to those of skill in the art upon review of theteachings herein though they are not explicitly set forth herein.Further embodiments may be formed from a combination of the variousteachings explicitly set forth in the body of this application. Evenfurther embodiments may be formed by combining the teachings set forthexplicitly herein with teachings set forth in the various applicationsand patents referenced herein, each of which is incorporated herein byreference. In view of the teachings herein, many further embodiments,alternatives in design and uses of the instant invention will beapparent to those of skill in the art. As such, it is not intended thatthe invention be limited to the particular illustrative embodiments,alternatives, and uses described above but instead that it be solelylimited by the claims presented hereafter.

1. In a method of forming a multi-layer three-dimensional structure,including: (A) forming a plurality of successive layers of the structurewith each successive layer, except for a first layer, adhered to apreviously formed layer and with each successive layer comprising atleast two materials, one of which is a structural material and the otherof which is a sacrificial material, and wherein each successive layerdefines a successive cross-section of the three-dimensional structure,and wherein the forming of each of the plurality of successive layersincludes: (i) depositing a first of the at least two materials; (ii)depositing a second of the at least two materials; and (B) after theforming of the plurality of successive layers, separating at least aportion of the sacrificial material from the structural material toreveal the three-dimensional structure, wherein the improvementcomprises: in association with the formation of at least one of thesuccessive layers, dividing the layer into a first thin sublayer and asecond thicker sublayer and depositing a primary structural material ina lateral region of the first sublayer to form at least a portion of thesublayer, and thereafter planarizing the primary structural material toa height that bounds the first sublayer, where the thickness of thefirst sublayer is similar to a known or estimated effective workhardened thickness (e.g. preferably having a thickness between 1/3 and 3times that of the estimated or known effective work hardened thickness,more preferably between 1/2 and 2 times that of the estimated or knowneffective work hardened thickness, even more preferably within 2/3 and3/2 times that of the estimated or known effective work hardenedthickness, even more preferably between 4/5 and 5/4 times that of theestimated or known effective work hardened thickness, and mostpreferably between 9/10 and 10/9 times that of the estimated or knowneffective work hardened thickness) or less than a known or estimatedeffective work hardened thickness induced by the planarizationoperation, and thereafter depositing the primary structural material ina lateral region of the second sublayer, and thereafter planarizing theprimary structural material of the second sublayer.
 2. In a method offorming a multi-layer three-dimensional structure, including: (A)forming a plurality of successive layers of the structure with eachsuccessive layer, except for a first layer, adhered to a previouslyformed layer and with each successive layer comprising at least twomaterials, one of which is a structural material and the other of whichis a sacrificial material, and wherein each successive layer defines asuccessive cross-section of the three-dimensional structure, and whereinthe forming of each of the plurality of successive layers includes: (i)depositing a first of the at least two materials; (ii) depositing asecond of the at least two materials; and (B) after the forming of theplurality of successive layers, separating at least a portion of thesacrificial material from the structural material to reveal thethree-dimensional structure, wherein the improvement comprises: inassociation with the formation of at least one of the successive layers,depositing a primary structural material in a lateral region of thelayer to form at least a majority of the one successive layer in thelateral region, and thereafter planarizing the primary structuralmaterial to a height that bounds or exceeds the desired height of the atleast one successive layer and such that at least a portion of theprimary structural material is work hardened, etching into the primarystructural material to form one or more openings that extend into theone successive layer in a least a portion of the lateral region toremove at least a portion of the work hardened primary structuralmaterial.
 3. The method of claim 2 further comprising depositingstructural material into the one or more openings after etching.
 4. Themethod of claim 3 wherein the depositing of structural material into theone or more openings occurs during deposition associated with formationof a subsequent successive layer.
 5. The method of claim 3 wherein thedepositing of structural material into the one or more openings occursprior to being a deposition associated with formation of a subsequentsuccessive layer.
 6. The method of claim 1 where curvature duringformation of the structure is reduced by forming the structure on athick rigid substrate.
 7. The method of claim 1 where curvature duringformation of the structure is reduced by plating material periodicallyon the back side of the substrate as a thickness of deposited materialon the front side of increase.
 8. The method of claim 7 wherein thematerial plated on the back side of the substrate is planarized after itis deposited.
 9. In a method of forming a multi-layer three-dimensionalstructure, including: (A) forming a plurality of successive layers ofthe structure with each successive layer, except for a first layer,adhered to a previously formed layer and with each successive layercomprising at least two materials, one of which is a structural materialand the other of which is a sacrificial material, and wherein eachsuccessive layer defines a successive cross-section of thethree-dimensional structure, and wherein the forming of each of theplurality of successive layers includes: (i) depositing a first of theat least two materials; (ii) depositing a second of the at least twomaterials; and (B) after the forming of the plurality of successivelayers, separating at least a portion of the sacrificial material fromthe structural material to reveal the three-dimensional structure,wherein the improvement comprises: forming at least one layer such thata primary structural material on the layer is provided with an uppersurface configuration, planarizing the upper surface, and thereafterforming notches in the planarized surface in a desired pattern where thenotches provide decoupling of stress located in separated regions ofstructural material.